Windows 7 Ultimate originally took up 15GB of space on a fresh install. 
Now it's stitting at around 18-19GB.
You could go for a 60GB drive and be comfortable.
I went with a 128GB drive, because I err on the side of caution, and to keep myself open to options. 

spitfire5792

Hey guys looking to maybe pickup my first SSD for my build as an OS holder. How big do I need for windows 7 ultimate, also any good deals now looking to spend little but I know certain brands for SSDs are bad and some are amazing.

Any input is very helpful.

 
Windows 7 takes about 10 GB with Hibernation disabled.
 
The new generation SSDs are just starting to come out. The Vertex 4 was released by OCZ earlier this week. What is your budget?

 
I got a 120GB Corsair Force 3 SSD drive from NewEgg for $135 (including the mail in rebate) about a month ago. It's plenty for the OS (which is Win 7 Ultimate btw), BF3 (Origin), MS Office 2010, and various other little apps. Boots pretty quick too and I'm always the first in game on BF3.
That being said, I would be careful getting a small (ish) SSD. While it may be great for the OS, I've already experienced what happens if they get too full (it's desirable to have them around 50% and 75% full - or at least that's where I've found mine works best). The only way I would really want to use something like a 32GB drive is for the OS only. That would mean putting Program Files as well as user profiles on another HDD (probably platter...?)
I hope this helps!

120GB is the smallest I would go and I wouldn't recommend going below 60GB. I own two OCZ Vertex 3 120GB SATA 6Gb/s VTX3-25SAT3-120G SSDs. They've been great. Amazon, TigerDirect and Newegg are currently selling them for $139.99 (after a $20 MIR) with free shipping.  I don't mind moving my Desktop and Documents to another drive but games and frequently used apps need to be on the SSD. Save your money and wait for the prices to drop if needed.
 
Microsoft recommends "16 GB available hard disk space (32-bit) or 20 GB (64-bit)" and it's a fair estimate IMO. Windows Update requires an estimated 750MB (32-bit) and 1050MB (64-bit) for Service Pack 1 (SP1) and there's plenty of other updates. Office is another story. 
 
I posted this the day after I installed Windows 7 (64-bit) on my main system's SSD. 

david12857 

daviangel Ditto. 
The Microsoft winsxs and the installer folders just seem to grow and use up more space the longer you use it. 
Here is a printout from WinDirStat (highly recommended to figure out where all your disk space went) on my rig and note that over 1/2 of my 96GB SSD is already being hogged up by Windows 

51.2 GB C:\ 
30.6 GB C:\Windows 
10.3 GB C:\Windows\winsxs 
  9.6 GB C:\Windows\Installer 
  2.9 GB C:\Windows\assembly 
  2.5 GB C:\Windows\System32 
  1.3 GB C:\Windows\SysWOW64 
  1.1 GB C:\Windows\Microsoft.NET 
etc... 

I'm glad I read your post. I installed a new 120GB SSD yesterday and was going to get my usage when I noticed hiberfile.sys was stealing 9.0GB and I need to disable Virtual Memory. My Windows directory is only 16.4GB. This is new install of Windows 7 Ultimate 64-bit. SP1 and all security updates have been installed. 

 

EDIT: Here's one of my older systems. Windows 7 Ultimate 64-bit (RTM) has been installed since 9/2/2009. It has SP1 and all Windows Updates installed too. 

 

 
I found 11GB of junk on there too.  

 
This is what the SSD looks like today.

How do they work when you install an OS to one while using other drives for everything else. DO you have to move the program x86 folder to another drive to save to that?

Had a 40GB Intel SSD as a boot drive. To small, would not go below 60GB but preferably 100GB+.

So from what you guys are saying it is pointless to get an ssd just for the os. I play tons of games and go back to old. Ones all the time and it seems like I should just wait until ssds hit 500gb without being rediculously priced.

All you get is faster boot time though right? Or does windows explorer run faster, I was thinking no since the programs will still be on the hdd

AB Was Here per Request... 

spitfire5792

http://www.newegg.com/Pro...x?Item=N82E16822148591


Any input about these, it is a hybrid drive, I've heard good things but will I see as big of a difference?

It looked great 2yrs ago but it's priced so close to bigger SSDs. Another thing to consider is your motherboard's SATA support. Is it SATA 2 or 3? SATA 3 SSDs are backwards compatible but you will take a performance hit. My GIGABYTE X58A-UD3R motherboard has SATA 3 ports but it's still a little too slow for my SSD. I don't mind but it's something to consider. SATA 3 support shouldn't be a problem with newer motherboards.
 
 
Thanks AB!

Last question, http://www.newegg.com/Pro...x?Item=N82E16820139601
 
or
 
http://www.newegg.com/Pro...x?Item=N82E16820148348
 
Also what if any are the differences?

I bought into the SSD scene early on with a 40GB Intel SSD, and while yes it did work as an OS drive as the months went on I began kicking myself in the ass for getting one that small. Just fighting to keep open enough space to defer performance degradation, so I just went ahead and got the Samsung 830 128GB SSD, and it is awesome! Never ever had a problem with a Samsung product and this thing is one of the fastest most competitively priced SSDs on the market. They have a 64GB model as well if there is a price concern, but that is the absolute lowest I would go. And be sure to optimize your system to free up space on your SSD.

Okay so after all this I went with the crucial m4 128gb that was recommended, looks to be the best for me and my uses. Anyways I have never used an SSD before so if someone could give me instructions as to what I need to do to install an OS properly on it and have my two old drives as i guess slaves to be used just for storage purposes ( my documents, basically the user stuff that gets saved that doesn't really require loading).
 
If someone could give simple step by step instructions or point me somewhere that has them I promise to love you forever.
 
Thanks for everyone's help on this!

spitfire5792

Okay so after all this I went with the crucial m4 128gb that was recommended, looks to be the best for me and my uses. Anyways I have never used an SSD before so if someone could give me instructions as to what I need to do to install an OS properly on it and have my two old drives as i guess slaves to be used just for storage purposes ( my documents, basically the user stuff that gets saved that doesn't really require loading).

If someone could give simple step by step instructions or point me somewhere that has them I promise to love you forever.

Thanks for everyone's help on this!

 
Crucial M4 is a very good choice and used to be the dominating SSD in the last few months.
 
For install, all you have to do is go to your BIOS/UEFI and change the SATA drive to ACHI instead of IDE. Then install Windows as normal and enjoy.
 
SSDs will not only speed up your boot up but your Windows experience in general. All your programs and software will open faster, Windows will be more responsive and "snappier." You can install all your big games on an external drive since load time in games are normally insignificant.

spitfire5792

What about the whole hibernation and page file thing to save space...should I do that stuff too? If so, how....I feel so needy, I haven't known so little about a computer component since I was 5 and hadn't touched a computer.

I don't use hibernation so I deleted the file, the page file I left on the SSD but reduced the size to 2 gigs.
http://www.sevenforums.com/tutorials/819-hibernate-enable-disable.html