Then that's great.
I would also recommend highly Gears of War series if you already dont have them. There's a rerelease pack coming out with Gears 1 and 2 plus all DLC next month so get that.
And like I said, get Red Dead Redemption.
With regards to Dragon Age Origins, it's a WRPG that has sorta like Lord of the Rings style setting where you can create your own character and select the race of your chracter and basically embark on an adventure, kill enemies, build relationships etc the usual stuff you do in RPGs. It's definitely not like Mass Effect. I'm also recommending Dragon Age Origins because of Dragon Age II that's coming out in March. It's a great looking game with lots of improvements here and there from DA:O. You can certainly start from Dragon Age II but you can also import save files from DA:O which could also shape how you play in DA II.
So if you want, get the Dragon Age Origins Complete Edition where it gives you all the DLC plus the Expansion, Awakening for a good price now.
