Worth Upgrading Dell...?

I currently have a Dell XPS 400 with the following specs:

Pentium D 930 3.0 ghz (locked BIOS - so no OC'ing)
2x1 GB Ram at 533 mhz
7900 GS (OEM) (PCI-E)
X-fi Soundcard
Dell 375 watt psu
Windows XP Media Center (not planning on getting Vista anytime soon)
BTX insides (reference to motherboard and power supply location)


I use this computer all the time for work related things and some decent gaming every now and then (Oblivion, FEAR, C&C3, Half-Life 2 Ep. 2, etc.) at 1280 x 1024. I am pretty happy with it, but am gradually noticing that in newer games, my performance is less than desired. I'm not expecting to play Crysis or anything very new and demanding, but would like to see a decent fps increase in the games I currently own (or anything released in 2006 or before) and also increase my satisfaction with this computer in general. Currently, I am planning on using this computer as my primary computer for at least 2 more years.

Two questions:

Is it worth upgrading anything on the computer? Perhaps the processor/motherboard?

Is this technically (it is a Dell) and financially feasible ($150-$250 range)?

Thank you for your time.

~Zack

Edit:

Current alternatives:

Do nothing (I'm currently thinking this is the best opinion).

Sell my computer for a couple hundred bucks now, not have a computer for awhile, save up a couple hundred bucks and build a new computer sometime next February (good idea, but not my favorite option for a variety of reasons).

Swap the 7900 GS with a new HD 3850 I recently found out I can get from a friend $130 (why so cheap? - the deal also involves trading some old hardware) (could be good - but will my processor severely limit the card to the point where it is not worth $130 bucks?)

Another good video option is 8800GT, BUTTT your psu won't cut it. Need at least 450W.

Just go give you a point of refrence see my computer specs in my signature. As far as games go I am able to run Crysis at medium settings with only water set to high and NO AA. The game runs well in my opinion. That was with 1GB of ram (just upgraded to 2GB last night) My video card isn't as good and you have a dual core processor, with the 2gb of ram you should be pretty good. If you are planning a new computer in 2 yrs and with what your computer is currently used for it should be pretty decent until your next computer.

It seems that upgrading the processor is financially a bad idea, as I would most likely need to buy a new motherboard, power supply and case.

Furthermore, my question: Would it be generally foolish (considering my processor) if I upgraded just the video card to a 3850, 3850 or even a 8800gt? What if I waited a few months and waited for a price drop? Would it be worth it then? Note: According to several sources here and on the Dell forums, my power supply will be able to handle all of those cards.

I would probably just sell the Dell and build a new PC. Prices are dirt cheap on just about everything right now. I would go with something like this:

$240+ - 8800GT
$83 - e2160 (OC to 3.0ghz)
$95 - P35 Gigabyte mobo
$60 - 250gb Sata HD
$40-60 w/rebate - 2gb Corsair XMS or Crucial Ballistix
$30 - DVD burner
$30+ - mid tower case with 120mm intake/exhaust fans
$40+ - decent PSU, maybe a Corsair 450vx (buy.com)

I'd step up to a 8800GT or something. It may be bottlenecked now but at least you're using the most out of your CPU, and whatever you buy later will get a nice speed bump without having to buy a new video card.