Keep your 3G man, it's awesome!
Update to the very latest firmware using iTunes.
Then quickpwn it, point and click. DOwnload version 2.2 at
www.quickpwn.comLastly unlock it to TMobile using the free yellow snow software here
http://blog.iphone-dev.org/post/67797811/dont-eat-yellowsn0wYour unlocked 8G 3G is now worth about $500 because it's unlocked.
Good luck