It's unlikely that certain games don't work on 64-bit systems as the kernel automatically works in emulation mode (wow64).....in this mode the 64-bit subsystem is basically hidden. The problem is more likely to be linked with something else. Have you tried the compatibility modes as first port of call?

NoD32 supports 64-bit, as does any other decent AV solution. I'm not aware of any 64-bit virus's/malware though.

As far as games go, most games (particularly newer games) will have improved performance in a 64-bit OS because all 2GB of RAM (32-bit software limitation) is accessible to the game like RSColonel stated, in 32-bit systems, the RAM limit (4Gb visible but only 3GB accessible) is also affected by VRAM and the Operating System constantly using background resources.

Well, from what I can see from the Star-Force website, lots of old Starforce games are not going to run on Win 7 or on 64 bit systems and Starforce couldn't care less (unless publishers want to pay starforce again and update old games!). That's why starforce games should be avoided I guess - there's more of a chance that you waste your money on the game because it won't be supported in future.

Check out these links on the starforce home page:

http://www.star-force.com/support/users/windows7/
" * Protection versions below 5.5 do not support Windows 7.
Users of products that protected with 3.x/4.x/5.0 versions should contact the protected program developers or publishers to obtain Windows 7 patches, or use previous Windows version to run the products.

StarForce offers FREE re-protection for all the developers and publishers of the programs that utilize version below 5.50 to release the appropriate patches. Please contact your sales manager for re-protection and further details.*

* Protection versions 5.5/5.6 partially support Windows 7.
Due to constant changes within Windows 7 during its development process some 5.5/5.6 builds may not fully support this OS. In case of failure please update the protection driver through the protect.exe utility or use a protected program developer’s patch to be able to run the protected programs in Windows 7."

Also check out

http://www.star-force.com/support/users/64bit/

"Older than 3.05

These versions will never be able to work with 64-bit OS.

StarForce offers FREE re-protection for all the developers and publishers of the programs that utilize version below 3.05 to release the appropriate patches. Please contact your sales manager for re-protection and further details.*
3.05 and later These versions support working with 64-bit OS with the corresponding restrictions in case of Windows Vista x64 (described above)."

So, the big question is "What games do I have on my system that are Starforce games and won't work with Windows 7?"

Just another reason to avoid SF all together.