Most 32-bit Windows software can run flawlessly under 64-bit versions of Windows, so you can continue using most of the applications you already have. Those that have 64-bit versions usually list both on download.com, letting you choose which to download/install. (Just search for the name of the program to see all available versions.) While searching, as a general rule, the programs are designed for Windows x86 and compatible with Windows x64 unless otherwise stated.
Hope this helps,
John
I am planning to build a new computer tomorrow and am planning to instal Windows 7 Home Premium 64-bit on it. I have checked the Windows 7 compatibility site and found that all my hardware is compatible with 64-bit.
Now coming to the software part, I usually download most of my softwares from download.com. Now my question is that if I want the 64-bit version of the software, how can I download it from download.com. I have found many softwares which in the same version supports both 32bit and 64bit. But what about the softwares which have different versions for 32 bit and 64bit?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic