Yeah as the title says, just bought a X360 kinda impulsive buy but anyways. I know I wanna try out Halo and Gears of War 2 since that one didn't come to PC...
But I figured I should ask you guys what more X360 exclusives I should try. Both Mass effect games I have so you don't have to mention them. A game that looks kinda fun is Crackdown but what do you guys think about it?
Would appreciate some help from you! Thanks

Gears of War 
Gears of War 2 
Splinter Cell: Conviction 
Limbo 
Alan Wake 
Banjo-Kazooie: Nuts & Bolts  
Forza Motorsport 3  

Well If you can find dead rising on the cheap it might hype you up for 2.

Dead Rising is guwd.

gratz bro.  get you some left 4 dead.

Wow thats fast! Yeah so Gow 1 I've got on the PC and loved it so I'm pretty sure I'll buy the second one. Alan Wake sounds very promising and will probably too be a buy in a near future.  Splinter Cell: CV I tried it at a friend and yeah its really cool and all but for some reason that didn't really appeal to me. I don't know if it was all that stealth stuff or something but it feels like a game I will play for a little while but never more play again :/ aside from that your sugesstions were great Ahmad_Metallic! 
@Hockeymask27 and @TheSeductiveMoose: Yeah Dead Rising sounds really fun as I really like everything with zombies in it! Will buy for sure thanks for the suggestions!

@BlackJedi: Yeah I too played that one at my friends house and since its zombie killin' thats a definite buy!! Both the first and second

Crackdown is ok, but it wouldn't be one of my first recommendations.  I'm just gonna list some of my favorites in no particular order, and hope I don't end up listing ALL of the exclusives :p   Also, pardon me if I happen to post something that isn't exclusive:
 
Alan Wake
Condemned 1 and 2
Fable 2
Lost Odyssey
Magna Carta 2
Project Gotham Racing(I'm not a huge racing fan, but those are pretty good)
Saint's Row(the first one...don't think it ever hit PS3) 
TooHuman(I didn't really love it, but I feel it's worth a rental or something)
Viva Pinata 
 
Edit:  I totally forgot to list any XBLA games, so I'm adding them here:
 
Braid
Limbo
Splosion Man
The Maw
Deathspank
Trials HD
Misadventures of P.B. Winterbottom
Shadow Complex

L4D 1 and 2 since you seem to like Zombie killin'.  Also, my 360 just broke and I bought a PS3.  I'll trade 360 exclusives for PS3 exclusives! :P

@metalhead87: Many great tips there thanks! Will probably just rent Crackdown to see if its anything for me, anyways its not that expensive on the preowned market though. I liked conemned 2 but since the first one didn't come to Ps3 I haven 't got that chance to try it and would be fun to see a bit more backstory. And PGR sound fun too and im a bit of a racing fan. Will probably rent Too Human just to try it out even thoug it didn't receive any good reviews. Saint's Row 1 is a must buy cause I love the second one !
@xobballox: yeah these two are also must buys and will try in a not to far future and maybe we'll trade someday! 
Again thanks for all great suggestions :D

Personally I would take it back and get a PS3 instead as it has a lot more fun looking exclusives in my opinion. I have had a 360 since shortly after it came out and I have yet to play a game on it that I couldn't get on my PC, which is why me 360 has been collecting dust for years now, while the PS3 has had some actual exclusives. Each their own I suppose.

Also since Im a bit of a racing dude I like Gran Turismo so how is Forza Motorsport 3? Better, bader etc? would be fun to hear from someone who tried both

crusader8463: Yeah I know what you mean but I so wanted to try GoW2 and Halo series, Forza Motorsport 3 to name a few. and since I got this one very cheap I thought why not?  Will see if I sell it after awhile though ;)

" BlackJedi: Yeah I too played that one at my friends house and since its zombie killin' thats a definite buy!! Both the first and second "

" @ShaunassNZ:  Okay thanks guess it's just gonna be L4D2 then :) GoW2 is a must buy and so is Forza3, Dead Rising and maybe Fable 2. But do you think that I should get Halo 3 OR Reach shouldn't I get the other if I just get one of them? "

Only gonna list exclusives :
      
Geometry Wars 2, Shadow Complex, Space Giraffe, Rez HD, Marble Blast Ultra, Lode Runner, and Trials HD are great games
Carcasonne and Settlers of Catan are great board game conversions
Rockstar Table Tennis is the world's greatest table tennis sim
Omega Five and Raiden Fighters Aces if you like SHMUPs
Fable 2 is pretty neat
Forza 3, PGR4, and Hydro Thunder Hurricane are great racing games
Banjo Kazooie Nuts & Bolts, the world's only engineering sim
Alan Wake, Halo 3, Gears of War 2, and Dead Rising 1 are great action games
Blue Dragon, Lost Odyssey, and Tales of Vesperia if you like JRPGs
Culdcept Saga if you like collectable card games
The remakes of Marathon, Perfect Dark, and the Banjo Kazooie games are good if you're on a nostalgia trip

Also, the 360 version of Bayonetta is superior

Bioshock if you haven't tried it yet, as well as Super Street Fighter 4 if you are into the fighting genre.

Fable 2, Alan Wake, Saints Row 1+2.

red dead, gta 4, saints row 2, mass effect 1 & 2, oblivion.

street fighter

fable 2 is good. crackdown is alright. there wasn't really any story once you get into the game. there's barely any sound if your walking around.