In need of an upgrade, though cannot decide which part to replace

[Zeos]

I'm going with a budget of <$200 at this point.

Ever since I've gotten my new monitor, a 1920x1080 beast, I've noticed that my once dream machine is starting to chug, unfortunately I'm dumb and can't figure out what I need to upgrade. At this resolution, even TF2 is giving me lag, though I'd like to run newer games like Bad Company 2 a little better.

[B]This isn't a major upgrade in any way, shape or form, due to the budget, I just need to know what I should upgrade in a short term basis.[/B]

My current specs:

OS: Windows XP (Planning to upgrade to 7 [I]eventually[/I] when I get enough money.)

Graphics Card: EVGA GeForce 9800 GT Superclocked 512 MB

CPU: Intel Core 2 Duo E7300 2.66 GHz

RAM: 2 gigs of mediocre generic RAM,( have given me some trouble but overall reliable.)

PSU: Another generic piece, a 560 watt PSU.

Cooling: Some generic case fans, though even though the main fan barely works, my temps never pass over 75 Celsius even when doing intensive work. Idles at around 30 degrees.

MoBo: EVGA 680i SLi socket 775. (Outdated, yes I know).

SoundCard: built in.

I have access to many Canadian stores such as TigerDirect and some Factory Direct outlet, as well as most major electronics chains such as BestBuy or FutureShop.

[Superscatman]

TF2 should not lagg.

I have a 8800 gts and a e4500 and I don't get lagg with everything maxed at 1680x1050

[Zeos]

Yeah I know, I've reinstalled the game a million times and it still lags in fierce firefights, I believe it may have to do with my RAM though.

[weeman007]

If you upgrade to Windows 7 it may fix the problem. Not because Windows 7 is better (even though it is) but since you have XP I'm assuming you haven't cleaned up your computer in a while. A good format would solve 50% of your lag problems I'm guessing.

[Blarg190]

I have some real issues running bad company 2 at 1680x1050 with my maxed out 9800gt, I have some shit in the works to get a new card atm though. Gtx 275 anyone?

[EBS-Gamer]

You should just save up and get a whole new system.