Update - September 17, 2016 Busy rounding up the bits and pieces to put the computer together.
Took the OEM CPU Cooler apart and cleaned the dust out of the fins and fan blades.
Cleaned the old paste off the cooler using Costco Eyeglass Cleaner and coffee filters - worked great!
It's now drying off pending re-assembly and mounting to the CPU and MB.
It's amazing how sticky the dust on the fan blades is. I used a toothbrush to get the worst of it, and then sprayed with the Eyeglass Cleaner and used a coffee filter to wipe it down.
Here's a tip: Instead of buying those expensive Canned Air bottles to blast the dust out of your computer, invest in a small air compressor.
I bought mine on sale a couple of years ago and it works great for this purpose. Just be sure to drain the tank regularly so it doesn't get water in it!
I can't remember exactly what I paid for it, but probably about the same as I would pay for 5 or 6 cans of compressed air at the electronics shop.
Just wait for them to go on sale. I got mine at a place called Canadian Tire which is a Big Box auto parts and general merchandise retailer.
I'm sure you have something similar south of the border.
Plus, I use it for the tires on my bike. So, win win.