depends... open up your case (hopefully it's a tower--
most likely the LH side cover will pull off, but this can
vary), and look down at the motherboard. if you see only
four, five, or six white-colored slots along the bottom LH
side, you only have PCI. however, if you see a longer,
BROWN colored one at the top (closest to the processor and
power supply), you have an AGP slot. i'm sure there are
other methods to use, but if you can open up the case,
this would probably be the quickest (and surest). also, if
it's not a tower case (the unit lays on its side vs.
standing upright), you're probably SOL-- but then again, i
could be wrong.
hth,
bryan
p.s. have you tried the hp/compaq website to see if you
can track down the info without getting your hands dirty
beforehand?