Will this video card be compatible and is it a good card?

Graphics card=ATI Radeon X1950 Pro HD PCI Express 256MB Video Card

Computer=HP Pavilion p6107c-b

Also if they power supply is too low can I add something like this,Diablotek DA Series 400-Watt ATX Power Supply PSDA400.|||your computer have a pci express 16x slot so you can use your video card,but you need a 450w power supply for your x1950 pro.