64bit support will basically come into play in the near future. The 64bit Windows XP is already out, but in my opinion there is no point switching since programs have to support it to.
Basically what it'll do with an OS and programs that support it once you get a processor that will support it is that programs will become faster, because they'll use 64bit processing instead of 32bit of now to run them.
Thats the good side of getting a 64bit CPU now to get ready for when these OS's and programs become available.
A good 64bit platform is the AMD Athlon 64 range
I hope this helps