Hi everybody.
Here's...
 
The Problem
 
Just got my GTX 560 in the mail the other day.  I followed the instructions, and ended up with a black screen at Windows login (Windows 7).  By that I mean that I get the dancing lights and the glowing Windows logo, but when it goes to initiate the graphics/mouse/desktop, it just goes black.  There's no glitching or anything, just a black screen.
 
I can use the card as a Generic VGA adaptor.  The problem only occurs after I install the drivers for the card.  Once I do that, I get a black screen at Windows login.  However, the fan works and Windows appears to load fine; I just can't see it.
 
I'm running with a Corsair GS600 on a stock ASUS Essentio CM1630 with 6 Gigs of RAM (motherboard M4A78LT-M with AMD Phenom II x4 830 Processor).  The motherboard has a 760G integrated graphics processor which shows up as ATI Radeon 3000.  I did all of the obvious things (disabled the integrated graphics at the BIOS level, uninstalled the driver, cleaned out the ATI stuff with DriverSweeper in Safe Mode).  The card is seated firmly and the 6-pin PCI-e connectors are plugged in firmly.
 
What I'm Looking For
 
I'm not looking for the typical responses to this sort of post ("Are the supplementary power connectors plugged in?"  "Have you used DriverSweeper in Safe Mode?" "Did you change the BIOS settings so that the PCI-e slot is the default?"  etc.).  I did all of that.  I'm looking for any known conflicts or problems that the GTX 560 might have beyond the 760G, or stuff that I might not have thought of.
 
Thanks in advance for any help.

Thank you for the suggestion, Scaryone.  Everything seems to be fine in the refresh rate department, though.

Yellow Fever, I've been using a custom install to loud the Graphics Driver and the Graphics Driver only.  Thank you, though.
 
But there's an UPDATE.
 
Like Scaryone, I was thinking that there might be a monitor problem as I'm using an old PnP monitor at the moment.  I figured it would be great if I could change certain vital settings (resolution, refresh rate) before getting to Windows 7.  Then I realized that I could in a limited fashion by starting Windows in Low Resolution (640 x 480) mode.
 
And voila!  It sort of worked.  It was actually running the GTX 560 as the primary display mode.  I could open up the Nvidia Settings and actually see it in action via the spinning Nvidia logo.  So something is definitely working.  However, there's...
 
A NEW PROBLEM
 
The card works in 640 x 480.  I can change the refresh rates as normal.  I can switch to 800 x 600 in the Nvidia Display Properties application and I can change the refresh rate.  However, if I try to set it to 1024 x 768 or higher, the screen goes black.  In theory, I should just have to wait 15 seconds for the image to come back, but it never does.
 
If, on the other hand, I go into the Windows Display Properties, there's a different story.  First of all, it reports my setup as "Generic PnP Monitor on VGA", which suggests some sort of problem, as my guess is that it should read Generic PnP Monitor on GTX 560.  If I try to change the resolution there, the screen goes black, and after about 20 seconds, it tells me that the Nvidia Driver stopped working but recovered (and it says Nvidia driver specifically, not VGA).  And it kicks me back to the lower resolution.
 
A lot of tl;dr going on here, I know, but has anyone run into that problem?  The card seems to be working, but for whatever reason it has a problem getting to 1024 x 768 or higher.  I'm going to try some experiments when I have more time after Friday, but for the time being that's where I'm at.

After trying my initial experiment, I figured it was the monitor and I had to buy a new one anyway.  So I bought it, and it's working like a dream.  Thank you for your help, Scaryone!  (And Yellow_Fever, too!)