32-bit vs 64-bit systems
Will all 32 - bit applications work on a 64 - bit windows 7 Operating System?
Windows 7 (64-bit) has 32-bit emulation layer and all applications that work in Windows 7 (32-bit) will work with 64-bit version also.
However, 32-bit drivers will not work.
Most will - some which make specific API calls may not (such as Anti Virus, Firewall, drivers or other "high level" software).