Ok then. Got the point. So it will be useless for me to spend a lot on a graphic card. I had the wrong idea. I will opt for one of the GPUs listed on the Adobe website and play it safe. Thankyou all of you for your advise and input.
As well as checking the Adobe site for tested GPUs, also check the Windows site for tested cards. I had been running Windows XP SP3 32 bit with an ATI 4870 card with 1GB RAM with PhotoshopCS4 (ver 11.01) with no problems. Since I have an i7 machine with 12GB RAM, I upgraded to Windows 7 64 bit when it came out.
The I downloaded and ran the Windows 7 Upgrade Advisor, which reported that my system could support Win 7 but that the ATI would not support the Aero interface, at least with currently available drivers. Then searching the Windows 7 compatibility center revealed that my card was 64 bit compatible but did not have the Windows 7 Logo.
Nonetheless, the installer set up Win 7 with the Aero interface. Things seemed to work fine for a while, but then I had numerous crashes and on rebooting I had the Windows 7 desktop with no taskbar, no icons, and no mouse pointer. I was essentially locked out. Starting is safe mode restored the desktop and I disabled Aero with no improvement. Then I tried the latest drivers with no improvement and then rolled back to earlier versions with no improvement.
In frustration, I selected an Nvidia card with the Windows 7 logo for 64 bit operatioin and also meeting Adobe's specifications, the Nvidia GeForce GTX 260 and am back in operation. I saw no need to get a high end gaming card and spent $200 at Newegg for superclocked version with 896GB of memory.
In searching the Windows 7 compatibility list there is a bewildering array of hundreds of cards with little guidance. One advantage of the Mac platform is that comparable hardware has already been chosen for you. However, you pay dearly for the convenience, and you currently can't run 64 bit PS.