I bought “The Witcher Enhanced Edition” (minus the Platinum?) a few weeks ago and I had to give up on it after a few hours. The game kept crashing randomly on my Windows 7 64bit machine, completely sucking the fun out of it.
From what I can tell, if you have Win7, buying it is a bit of a gamble. Some people have no trouble with it, others have the same issues that I had.
I even recall seeing an online game store that had the game listed as being incompatible with Windows 7.
If you still have a Windows XP CD/DVD lying around somewhere, you can set up your PC to dual boot Win7 and WinXP (there are plenty of simple guides on how to do this if you do a google search). That would solve any potential compatibility problems with “The Witcher” and Win7.
Currently playing: DayZ; Crusader Kings II; Borderlands 2; Arma 3