Solidsnake: If you aren't aware, go to the start menu, then Computer. Go to the drive that your OS is installed, likely C: and find Program Files (x86). This is where your 32-bit programs are installed to. The majority of the programs out there are designed for 32-bit. Your 64-bit programs are installed to C:\Program Files\. If you don't want any 32-bit programs installed, uninstall everything that is in your 32-bit folder, lol (I don't recommend it). All in all, 64-bit Windows Vista/7 has no problems running 32-bit software.
As borrowed from Microsoft's FAQ (http://windowshelp.microsoft.com/Window ... mspx#EBBAC) -
Can I run 32-bit programs on a 64-bit computer?
Most programs designed for a computer running a 32-bit version of Windows will work on a computer running 64-bit versions of Windows. Notable exceptions are many antivirus programs, and some hardware drivers.
Drivers designed for 32-bit versions of Windows do not work on computers running a 64-bit version of Windows. If you're trying to install a printer or other device that only has 32-bit drivers available, it won't work correctly on a 64-bit version of Windows. If you are unsure whether there is a 64-bit driver available for your device, go online to the Windows Vista Compatibility Center.