Ok, after talking to a Dell salesperson, the best card I can upgrade to is a NVIDIA GeForce 9800GT. I currently have a Geforce GT 220. I cannot get a card better than that because(supposedly) if I upgrade my power supply(300W) any further, it may blow up the components on my motherboard. So here is my question: How much better is the 9800GT compared to the GT 220? Is it worth the money to upgrade? Will I be able to notice the frame rate increase(if there is one)?
Because the question is based on incorrect information.
The 9800GT is significantly better than the GT 220 but if you want the best card for your computer it is not the 9800GT. Either the HD4770 or HD5750 can be run on such a PSU and are better cards, the HD5750 largely so and it is also DX11 compatible.
Oh yeah, what card you should get depends on your resolution. The 9800GT would be a good card at resolutions up to 1280x1024(1440x900) while the HD5750 will be great but kind of a luxury if price is an issue. If your monitor's native resolution is above that (ie 1680x1050+) the HD5750 is definitely the card to get.
Also the idea that a better PSU would make your system explode is laughably incorrect. I wouldn't recommend it though because Dell usually uses a unique form factor for their PSUs and purposely designs their systems to be hard to upgrade. It's not worth the hassle when your current PSU can already run some pretty nice cards.
So, if the 4770 runs great on luckyyellow's computer, and the 5750 is better and uses a little bit less power, I should be fine. Thanks for the reply. I guess i could always sell the card if it doesn't work in the end.
I can say this having two of them that they are very good cards and they perform very well. However not all of them are the same, the older 65nm versions run hot compared to the 55nm versions. The green or E versions are to be avoided regardless of psu due to issues and compatibility with some boards while having lower clocks with little head room for overclocking. So if you can if you want nvidia a 55nm non green or EE edition is your best bet but if you want better performance a 4770 or a 5750 is your best bet.