Quote Originally Posted by shaithis View Post
32 and 64bit are inter-changeable since Vista.

You can just re-install with the 64bit media using the same key.
Not exactly correct ether, Retail it's ok, OEM it's not.
I've been having some "fun" at work with Win7 OEM keys and discs.
Sometimes they are interchangeable and sometimes not.
eg 2 pc's from different suppliers, both win7 pro 64bit.
pc1 with except ether license number.
pc2 will not except pc1's key
So there is obviously some difference between the OEM licenses/installs, I don't know what as they are both supposed to be the standard win7 pro 64bit OEM

On CUDA, it depends more on the plugin's you use some do specifically use CUDA only.

Scratch disk size will depend on the settings and files you use, setting the location of the scratch disk isn't hard to do, it's in the photoshop preferences.

On graphics card rendering, while he's not mentioned any 3d stuff, there are a few things that do it, the main one is VRAY, this give photo realistic results and requires as much gpu as it can get and A LOT of vram, depending on the complexity of the scene, but 1.2gb of video card ram is the suggested minimum.
A gtx560 2gb card is your best bet as a minimum level card for VRAY