i can’t get my new card to be recognized

I’ve looked everywhere i can think of and can’t figure out whats wrong. i have an 8400 GS PCi-e card i installed. and i can only get graphics from my onboard video.

steps taken –
disable onboard graphics through device manager
change video priority to PCI-e through BIOS
installed drivers for new cards from provided disk and website
*note* there is no separate power cord on the card itself

computer stats –
motherboard – geforce 6100 am2 v1.3 (biostar)
power supply 380 watt (card asks for 300)
OS windows XP
processor AMD athlon 64 2.21
RAM 512 DDR 2 800

any other info you need let me know. i’m stumped