I know that the x64 Version of Windows 7 allows you to use more RAM, but is that all? My friend has a 64 bit processor but is currently running a 32bit version of windows. He only has 4gigs of RAM, but are there other benefits for him upgrading to the x64 Version of Windows 7.
Other than using all of his memory, it can be a benefit if he uses 64-bit programs extensively. As more programs become available that can use multiple cores and are native 64-bit, the 64-bit versions will become necessary. But right now the Winx64 versions put the 32-bit programs in the Program Files(x86) folder and use Windows on windows (WOW) to run them, which adds to processing time - it is not noticeable except in the various bench-marking programs.
There isn't anything a 64-bit program can do which a 32-bit program CAN'T do, with the sole exception of accessing more RAM. Most programs need a lot less than a couple GB of RAM, and so by themselves they don't need a 64-bit OS. The only exceptions are a few categories of applications such as video editors, batch processing of huge photos, large databases, etc.
But even if you only use 32-bit programs, if you run ENOUGH of them then collectively they can use up 4GB or more of RAM. In that case you're better off with a 64-bit operating system, because it will be able to keep all those programs in RAM without having to slow down to read them from disk as you switch between them.
The rule is: 4GB or more of RAM --> use 64-bit Windows (note that 32-bit Windows can't access the entire 4GB of RAM).
If you use 64-bit Windows, then don't worry if you can't find a 64-bit version of a particular program. In most cases the programs that actually need 64-bits have 64-bit versions available (Photoshop, for example). If there isn't a 64-bit version available, the program probably just doesn't need enough RAM to make a difference.