The way I see it you have two options:
1) Slave away, doing everything from scratch, and if you don't kill youself out of frustration produce a crappy game.
2) Use ut2k4!
Seriously, thats a very, very good suggestion. You're not going to top their physics!
Actually, for the ultimate in pimp-age, use Half-Life-2, which is/will be mind boggling. Ragdoll physics for human players
