Gears 1 and 2 (Gears 1 was the first must have game of this gen)
Left 4 Dead (bots are not as good if you aren't online, but if you like Zombies it will do)
Bioshock (my opinion on best game this gen)
Call of Duty 2 (campaign is great)
COD 4: Modern Warfare (I think the campaign alone is still worth it)
GTA IV (this game really is a masterpiece, not sure why so many criticize it)
Halo 3 (solid game)
Mass Effect
Oblivion

I dunno, you listed all shooters. IMO Gears isn't all that good. Halo 3 is amazing. mass effect and bioshock are great, you can miss out on the rest honestly unless you like shooters then pick up COD4.

I suggest: Nuts & Bolts if you're an old school gamer, its amazing.
Lost Planet
Ninety Nine Nights.

congrats on a great buy! If you like rpgs I would recommend Fable 2. Lots of DLC and quests to make the game worth the money.

I'd also go agaisnt fable 2. If you like RPGS fallout 3 will be the correct purchase.. fable 2 is way too short and way too easy. Wonderful game but it feels like a 29.99$ game, if you can get it really cheap get it but it's a massive disappointment as a product. and the DLC is pretty ass horrible.

I'm into RPG's and action or action/adventure games, also, fighters. I love pc shooters but i haven't played anything on console since i think perfect dark for N64
I like pretty much everything, i want to enjoy some pretty HD graphics though.
Oh, I like new/weird concept games (like katamari)

Congrats on your purchase. Get Gears 1 & 2, Mass Effect, ODST, LO, and 100's of other awesome titles. As a gamer, you cant go wrong with the 360. My favorite console this gen.

if you really wanted to show off your tv to bad you can not get a ps3, bluray and tru 1080p, none of that upconverting crap, but ps3 will upconvert regular dvds to look much better, my 360 looks like ass with reg dvds. on my 360 i like playing gears of war 1 and 2, halo3, halo3 odst, protptype, left for dead, halo wars, vegas 1 and 2, thats about it on my 360, the rest on my ps3, about rrod, im on my 7th 360, and my original ps3 and mt ps3 is my main gaming system, so you just never know, 360 had up to 60 percent fail rate, last stat i saw was 54.3 percent  august 2009, i had real bad luck, there a piece of shit, but usually not quiet that bad, all my friends are on there 3rd and 4th 360, all are on original ps3 to. ps3 fail rate around 6 percent.  good luck

Then I don't quite understand why he has decided on the Xbox. If someone is bringing it over from the US then how is the PS3 more expensive, which is what he stated at the beginning. They're both around $300.

You would have to ask him that question.  I would say it would have something to do with the future game purchases though (ps3 games are higher priced there).  I would imagine he can't get games from the usa on a regular bases. 

$50 mail in rebate also knocks the price down a lot as well.  You could get  2 older games or 1 newer one basically free.

I'll get:
GeOW 1 and 2
PES 2010 when it comes out
...
either Halo 3 or COD 4
either Lost Odissey or GTAIV
either Nuts and Bolts or Viva Piñata
Any advice?