dell inspiron 560
400 watt power supply (i'm willing to upgrade this to whatever necessary, so power is not an issue).
pentium dual core e6700 @3.2ghz
64 bit Win 7 home premium
8gb DRAM @532mhz
p45/p43/g45/g43 chipset supports PCIE-2.0
available slot PCI Express 2.0 x 16 (occupied by current card)
current gfx card AMD Radeon HD 6450 w/1gb memory
I have made no personal upgrades to this computer yet. It's now a year and change old.
Trying to keep the overall cost of graphics card upgrade under $250 (not including the power supply).
Currently I'm considering the 6870 w/4gb memory and a 500-650 watt power supply. That (according to Hardware Compare website) is theoretically ~7-8x better than what I currently have.