The newer ROMs have enabled the GPS. The have also upgraded the OS to Windows Mobile 6.1. Since you have Sprint I would just download the
latest release from sprint and put that on your PPC. Then if you want to read up on custom roms then do so. I love making my own ROM's because I can burn all my email settings and programs right in and when I have to hard reset, it only takes a few minutes and my phone is right back like I like it.
By the way you will need a USB cable and active sync installed to do the upgrade.