Roy,
Use of 32-bit Python25 is built in to ArcGIS Desktop 9.3.x arcgisscripting library. It will run without issue under WOW6432 emulation on 64-bit OS.
You could install a 64-bit Python as well, but ArcGIS would not use it. Also, I don't believe the 218 build of PyWin32 for Python25 has a 64-bit flavor.
Since ArcGIS won't use it you could load a more current Python for 64-bit use if you go that route.
Just be aware, it can be a PITA to reconfigure between Python versions depending on your programming and sysadmin needs.
Stuart