Feel like buying a game, suggestions

Hey i normally don't buy too many games, don't play too many games, and don't keep up with games. lol I am pretty dedicated to quake live (i dont get bored with this game a all), and aside from that i enjoy DoD:Source (TF2 "sometimes", played A LOT of L4d but got bored with it, didnt really like mw accept the story). Every now and then i like to buy a "good" pc game in hopes of liking it and having to get to play more than 3 games consistently but most of the time i get bored with it.

I gues im a multiplayer person, and not into single players (havnt even passed HL, Bioshock, oblivion etc etc)

BUt seeing as how i dont even play mp games aside from quake live, I want to take a break from it. So what is a good multiplyer game, that has a lot of reply value, and is somewhat new, as i will probably not buy another game for a while.

I was thinking L4D2 but i played many many hours of l4d until i became bored with the game (but at least this game got me by for half a year and then some) but do you think l4d2 is worth the new features and such.

I like fast person shooters thats my thing. So any suggestions, basically gooood reply value.

EDIT: BTW the rig is my specs is outdated. right now i have an AMD Phenom II 965 2 gigs of ddr3 ram, and an OC'ed 4850 512mb. monitor is 22" 1680X1050

L4D2 is a great game it has enough new stuff for me new Special Infected are cool and so are all the new weapons

L4D2 is a big improvement over the first gameplay wise imo. You could also try Killing Floor if you don't want to spend $50.

have killing floor spent a good amount of time but stopped playing

mw 2 but after price drop.

otherwise machinarium

Pre-order Serious Sam HD, it comes out tomorrow. :D

how about ghostbusters i know it isn't MP but it seems cool, and its on sale, which is why im leaning towards it

http://store.steampowered.com/app/9870/

get dragon age

if you insist on playing fps play tf2, its the best out there

but rpgs are better than fps

you just need to try

also you can do bioshock

its an fps, but one with a story, not just twitch shooting

how about ghostbusters i know it isn't MP but it seems cool, and its on sale, which is why im leaning towards it

http://store.steampowered.com/app/9870/

sabbath2gamer