Windows XP 64bit version help

most 32 bit software will work under 64 bit windows. Anti-virus software is one that sometimes wont. There is a 64 bit version out there just cant remember which one it was thats free.
I have used 64 bit a little and had no problems with games running on it. I dont have any 64 bit apps yet so I have stuck with 32 bit pro for now.

The free antivirus that runs on x64 is:
http://www.avast.com/eng/x64.html
Most of the retail AV works on x64, but that is the only free one that does (that I know of).
As far as anti-spyware: Ad Aware works, and I think Spybot S&D has been updated.

The software you may have problems with is any that require low-level hardware use. Some CD/DVD burnig programs and software firewalls have problems - most have x64 updates, however. Just make sure the software is at least 32-bit, as I don't think the old 16-bit programs will run at all.

As far as your TV tuner - I doubt it will work. I think all drivers have to be 64-bit.

This is natural. If you want to think of it as x64 has a "shell" in which it runs the 32-bit programs. The programs which will have problems running in x64 are the ones that need access outside of this "shell" (low-level access) - these have to be 64-bit.

In short, most all programs will run within the 32-bit shell except those requiring direct hardware access (virus scanners, disk utilities, firewalls, etc.). All hardware drivers have to be 64-bit, however.