Mass Effect 1 , Mass Effect 2 , Fable II , Halo 3 and ODST , Gears of War 1 & 2 , Forza MotorSport 2 & 3 (2 is better) , Blue Dragon , Lost Odyssei , Alan Wake , Splinter Cell Conviction , CrackDown 1 & 2 , Ninja Gaiden II , Bayonneta , Assassins Creed 1 & 2 , BioShock 1 & 2 , Oblivion , GTA IV , The Orange Box , L4D 1 & 2 , RdR , Cod 2 4 and Mw2 , PGR 3 & 4 , Fallout 3 ,  Batman: Arkham Asylum , Shadow Complex , Limbo , Splosion Man , Trials HD , Castle Crashers , Braid...

All those games are worth the money !

Or you can wait for :

Gears of War 3 , Halo Reach , KingDoms , Mass Effect 3 , Alan Wake 2 , Fable III , Forza MotorSport 4 , Assassins Creed BrotherHood , Fallout New Vegas , BulletStrom , Brink , RaGe , PGR 5 , Crysis 2 , Black Ops , Batman: Arkham Asylum 2...

Oh and if u like Sports Games then Fifa , Madden , NBA etc...

So many games hope u have money for all :)

Hm...no one ever recommends Kameo, Project Sylpheed or Halo Wars (I haven't played them yet as I'm busy with XBLA games at the moment, but those were the first 3 retail games I bought last week for the system).

360 shall be known as my strategy/building sim console: I already bought Halo Wars, RISK: Factions, Outpost Kaloki, Defense Grid, next ones will be Viva Pinata 2, Tropico 3, Toy Soldiers, Kingdom for Keflings.

If you're not interested in strategy or sim, here are two definite recommendations:
Rez HD (XBLA) and Psychonauts (Xbox original)

And listen to pearljammer, the wise man who not only likes David Bowie but also recommended the excellent HD remakes of my most favourite game ever: The Secret of Monkey Island 1 and 2 (available on XBLA/PSN/Steam/D2D)

Also, every 36o owner should make sure to keep this wonderful 2011 XBLA game on their radar: http://www.youtube.com/watch?v=DmSAQwbbig8

Well Kameo is indeed a great game and PDZ wasnt bad at all...

I loved the first crackdown at my firneds house, should i just get that one or the second 1?

Well I realized that my personal friends who also had ps3's, are very  immature, so I dont hang out with them. Just that and the culmination of everything thing else like xbox live and the games coming I decided to get a 360.

Wow great response, thanks a ton :D

Probably every game has been mentioned here. If you have a friend with Halo 3 tell him to lend it to you so you can play the campaign and get Halo 3 ODST instead so you don't to buy any map packs to get the full online experience. I wouldn't have bought that xbox though, I'd have waited for the Halo Reach 360 and if you're low on money a new $150 arcade just to make sure it has the Jasper motherboard [or is a slim] so you don't have to worry about the RRoD.

Thats what i wanted to do, but i have to think foward to getting a car, graduation high school, my job. Personally I want all 3 systems haha

Did not notice it on others lists but I love Toy Soldiers for XBLA and rather embarassingly  the Snoopy flyer game thing (pretends he is not sure what he is talking about).

Otherwise somebody who is starting from scratch should find plenty to do, when you look back and this goes for the PS3 it is suprising how many good games we have had already this generation.

Crackerlacking. Do not worry about the PS3 bretherin you have lost think about the far more sparce 360 gamers on VGC, in fact you have just become on of the 360 Spartans (Sony are the Persains for this purpose of this renactment) hopefully it will end better for us.

You should get alan wake (but make sure u buy it new so u can get the first dlc for free)

I you want rpgs then u should try the mass effect games and oblivion (don't buy fable 2 coz F3 is almost out)

And you should also try out ninja gaiden 2 and halo wars , both don't get recommended enough

 EDIT: And dont forget to try some arcade titles the best are : limbo, shadow complex, trials, geometry wars 2 and perfect dark