[Oxymoron238]

For starters, check out the stickies on that forum page. They'll tell you more about custom roms and how to unlock your phone (you have to unlock it before you can use custom roms). The stickies can give you some more details on that process.

After you've unlocked your phone, then you can search through any one of the other threads. Each one of those threads contain roms that you can flash to your phone. I can't really tell you which one is the best, because that all depends on what you are looking for (speed, stability, newest software, etc.).

I hope this helps, and happy flashing!

EDIT: Oh, you beat me to it mwalt lol!