I don't think you got bad value at all. Sure it's not a pimped-out gaming rig, but it's a very decent machine that will play games just fine. Sure, there are better video cards out there, but they do cost more money. Yep, you could build something cheaper yourself, but you have to build it and support it yourself too.
I don't think Dell screwed you at all. It's unlikely that the Dell folks know as much about gaming and video cards as we do. If you want to change something, I'd ask Dell to swap you for a GeForce 3 Ti 200 if they will. Even if you pay the price difference, that would still be a fair deal, since I don't see that they overcharged you. If you would rather have a more expensive but more powerful card, ask them to swap it for you. Make them pay for shipping though since it was their dubious advice.
In the future, ask on this message board before buying, and we can likely help you choose a very good "bang for the buck" gaming machine even from Dell if you want their support and warrantee. If you don't want to build your own, Dell is a good choice. In fact, although I build my own machines, I recommend my family and friends who are not technically savy to just buy Dell. I help them choose the system, everything works fine, and they get a good computer at a reasonable price. Oh, and they never call me with problems either.