Just took a look, and according to what I've seen... your motherboard doesn't have an AGP or PCI-E slot.
I don't know why Dell even sells machines without a PCI-E or AGP slot, but they've been doing it for years (although marketing the "upgrade possibilities" with their hardware). Low end to low-midrange PC's tend to have micro ATX mobos (actually Intel mobos if I remember correctly, with header pins for Dell's proprietary cases). So.. it'll be a bitch to swap out the mobo in the thing unless you're comfortable with cutting the plug on the cables for the power button, reset button, etc.
From the stock specs I've seen on the machine, it came with fairly slow RAM.. plus, that processor is a power and heat hog. I can see how the integrated graphics probably are slowing down your machine a good bit, so here's my suggestion.
Outside of building a new PC or purchasing a new one, get a PCI video card if you don't play any recent games. You'll see a decent performance gain with a GeForce 5 or 6 series PCI card, but you still won't be able to play many recent games. I'd also put some RAM in if you can..your PC came at base level with only 256mb DDR2 400mhz... you need at least a gig in there. Fortunately, a gig of 240 pin RAM is fairly easy to come by for cheap on Newegg or something... but will be WELL worth the investment.
Hope this helps man.. I honestly hate how Dell shafts their customers.. even most eMachines have a decent video expansion slot. They tout all of the marketing buzzwords, but leave you with a brand new system full of bloatware and few system resources to support it. If you're willing to toss about $80 into it, you should see a decent performance gain.. but unfortunately, you'll have to stick with games from a couple or three years ago.
