EDIT: My friend has Phantasy Star Universe and says that it is not as good as Blue Burst or Episode 1.
It sadly isnt.
This is the unfortunate truth. Good news, though, is that the next Phantasy Star game coming out will be much more similar to the last few in the series (I refuse to acknowledge Ep. III as a game).
There isn't much more to say, other than to re-emphasize what other people said in here. Bullet Witch is a no-no. I'd advise against Ninety-Nine Nights (and this is coming from someone that liked the Kingdom Under Fire games). As well, you can scratch PDZ off the list.
I'd say not to get Chromehounds just because very few people ever play it anymore, and after Halo 3 hits, nobody's gonna be playing (this seems to be the sad truth with lots of games).
As Bocom said, yes, Counter Strike for Xbox sucked.

Definitely save for Half-Life 2: Orangebox, though.
I thought Doom 3 was a bit of a disappointment.
Enchanted Arms got so-so reviews. If you need an RPG to hold you over until Blue Dragon comes out, then I guess you can go for it.
F.E.A.R. was all right, but I didn't like the PC or the 360 version, so meh.
Fable: Lost Chapters is good, but beware of save corruption on the game.
Not much to say on Lost Planet. I didn't really enjoy the singleplayer demo, but multiplayer was decent.
The rest are good choices, I think. Like Loki said, I'd throw Splinter Cell: Double Agent on there, as the multiplayer is a blast. Lego Star Wars games are good with other people to play with, but I believe Traveler's Tales is putting out an anthology game, so you may want to hold off on that.
Lately I've been stuck on Marvel: Ultimate Alliance. It took me a while to get into it (because I didn't have anyone to play with), but now I'm addicted. And I'm expanding my comic book knowledge as I play!

I can see why it got such good reviews, at least.
Shadowrun is decent, and there's a patch coming this week to aid with the online play problems. I don't play it, but my cousin loves it.
I have yet to buy Guitar Hero II, but I'm not even going to bother, since Guitar Hero III has already been announced for this Fall, and Rock Band is coming out before that.
And yes, Ryan, I am getting Xbox live.
<3