for the alltel users you have to put special installs on after you get the "new" rom and radio update. these enable the usage of the gps through the handset. check out this
http://forum.ppcgeeks.com/showthread.php?t=27180 it has the files you need to get the gps started. and get familiar with the whole windows before trying to upgrade to 6.1 i just udgraded to a custom rom today and ive had mine for about 5 months. so good luck and once your ready check this out
http://forum.ppcgeeks.com/showthread.php?t=33857 and just so you can get used to "hearing" this phrase. "your phone your fault"
laterz,
~chevy