don't pair a $300 video card with a $20 power supply and expect happy times. spend at least $80 on a 600w unit from a good brand like antec, cooler master, corsair, thermaltake, or ocz.
as for compatibility with your motherboard, that card will work in any pci-express x16 slot. also, there's no such thing as an "intel quad core q9500 (2.2ghz)". i assume your processor is really an "amd quad core phenom 9500 (2.2ghz)".
I am currently considering buying a 9800 gtx. http://www.newegg.com/Product/Product.aspx?Item=N82E16814133220 My current computer layout is as follows: Intel Quad Core 9500 (2.2 ghz). 3GB pc-6400 RAM. GeForce 6150SE nForce 430. NVIDIA 8500 GT. Will I be able to install the card with that chipset? Will this power supply be enough to handle the card well?: http://www.xoxide.com/casegears-black-steel-580w-psu.html