Nevermind. I just found your other thread. I didn't realize this was for a Dell PC. By the looks of it that's a TFX power supply. I can't be sure though. If I'm correct in my guess you should be able to upgrade to about a 400W power supply, which is probably enough to run some lower end graphics cards (check specs before buying anything).
If you want to make some upgrades to more power hungry components, I would do what Willdobo suggest, and just buy a new case and transfer everything over. That is, assuming your mobo will screw into another case. Unfortunatelly, Dell likes to use proprietary parts.