Unreal Tournament 3 or Halo 3? and some question....

I have an Xbox 360 and I've been wondering either to get Halo 3 or wait for Unreal Tournament 3.

just some questions:

-Can I still save vidoes with a 256MB memory card in Halo 3?

-On the xbox 360 version of UT3 will there still be NPC bots?

-Is ther Co-Op in UT3?

any suggestions?

well not including COD4 (I'm looking for a futuristic combat shooter), should I get Halo 3 or wait for UT3?

also could someone answer some of my questions too?