2 things. Your system probably does not support AGP 4X... check it out I may be wrong.
It did not fit? You may have bought an AGP card, and only have PCI slots on your system.
Do you know if your current videocard is onboard or a single card?
If on onboard make sure you can disable it.
You maybe stuck using a PCI TNT2 or PCI VOODOO3 for gaming cards. That's what Compaq's 'll do for ya.
Later,
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Lizard King - 00GT
>> 13.698 @ 101.2MPH - BONE STOCK, yes
BONE(even air filter) stock.
"I can do anything, I'm the Lizard King." - The Doors