I'm starting to mod again and I have to replace my graphics card. It'd running at 85 degrees C on load at 100% fan speed...
Which has been killing my PC overall and crashing me every 10 to 15 seconds of playing. I've been planning to get a full out upgrade
in preparation for Skyrim, but I'm not there just yet, so Iwant to replace my 8800 GT with something that's ideally a step up from it.
But will also work with my current setup. Here's my setup:

Power Supply: http://www.newegg.com/Product/Product.aspx?Item=N82E16817139018
CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16819115028
Memory: http://www.newegg.com/Product/Product.aspx?Item=N82E16820231098 * 2 (4GB)
Motherboard: http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3528165&CatId=3495
3X 7200 RPM Drives
Graphics Card: http://www.newegg.com/Product/Product.aspx?Item=N82E16814130303

I want to upgrade the card(ideally) with a setup that I wont need to buy a better PSU for, but will be on par or better than this Graphics Card.
Please help!!!

The Geforce 8800 design is over five years old and required a high end power supply when you could actually buy them new from Newegg.

"EVGA 512-P3-N802-A1 GeForce 8800GT 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card

OUT OF STOCK."

Last year's Radeon HD 5670 runs on a ordinary (not necessarily aftermarket average, but OEM) desktop PC's stock power supply and will do anything except drive a very high resolution large display. It is also sold for about $75 or so.

Thanks for your response!

I'm a bit partial towards NVidia cards though,(I also watch videos in CUDA acceleration) is that a really good card compared to similar Nvidia cards at that price mark? And are there any cards that have similar
power as that card for Nvidia?

Edit: Do you think this power supply can support Nvidia 4xx Fermi cards?

A 500 watt Corsair is a decent power supply that would support the middle level Fermis, 460 / 560, and downward. nVIDIA has been forced by their lack of an X86 processor of their own, to continue adding more layers of complexity to successive generations, so that the 480 / 580 Fermis are the biggest, most expensive, hottest running GPUs ever, and their lower powered GPUs derived from those very complex designs tend to remain very expensive, so that they simply haven't been price competitive at Low and Mid levels for two years now. The value just isn't there. To get the best bang for the buck at any level below the stratospheric, you have to buy Radeons.

Assuming that you understand that you will be paying too much, you can match the HD 5670 with a Geforce GTS 450.

Your power supply could even take on the GTX 560 Ti or 560 if you can afford them. Even the GTX 460 or 550Ti are rather significant upgrades over the 8800GT. If you need cheaper, then the GTS 450 that Gorath suggested earlier would be the lowest I would suggest if it must be Nvidia.