Power Supply and Graphics Card Compatiblity?

HP Intel Core 2 Quad 2.4
Model: M8517C-B

# Processor and Memory: Intel® Core 2 Quad Processor Q6600
# 5120MB PC2-6400 DDR2 SDRAM memory (1x2048MB 3x1024MB) (expandable to 8GB)

Hard Drive and Multimedia Drives:
# 750GB 7200RPM SATA hard drive
# SuperMulti DVD Burner with LightScribe Technology: 16x DVDR, 8x DVD+RW, 6x DVD-RW, 8x DVD+R DL, 4x DVD-R DL, 5x DVD-RAM, 16x DVD-ROM, 40x CDR, 32x CDRW, 40x CD-ROM

Audio, Video and Graphics:
# High Definition Audio, 8 speaker configurable
# Intel® Graphics Media Accelerator 3100 with 128MB dedicated graphics memory; up to 287MB total available graphics memory as allocated by Windows Vista

Ports/Slots:
# 2 external 5.25" (one available)
# 1 external 3.5" (one available)
# 2 internal 3.5" (one available)
# 1 PCI (occupied)
# 2 PCI Express x1 (available)
# 1 PCI Express x16 (available)
# Front panel 15-in-1 memory card reader supports Smart Media, xD, MultiMedia Card, Secure Digital (SD), Compact Flash I, Compact Flash II, Memory Stick, Memory Stick Pro, Memory Stick Duo, Memory Stick Pro Duo, RSMMC, MMC Mobile, MMC+, Mini Secure Digital, IBM Microdrive
# 6 USB 2.0 port(s) (2 front, 4 back)
# 2 FireWire (IEEE 1394) port(s) (1 front, 1 back)
# Headphone; Microphone (front)
# 2 PS/2; Digital Audio Out; LAN; Microphone/Line-in/Line-out; Rear speaker-out; Side speaker-out; Center (subwoofer); VGA-out (back)

Operating System:
# Genuine Windows Vista® Home Premium 64-bit edition with Service Pack 1

I am currently looking for a new power supply [http://www.newegg.com/Product/Product.as... and graphics card [http://www.newegg.com/Product/Product.as... but i keep reading that your graphics card will not work unless it is compatible with your power supply? I would like to know if the power supply and graphics card i have chosen are compatible with each other and with my current computer? I know very little about computer and am very confused with all the numbers and voltages and ddr terms ect ect.... HELP ME PLEASE