You probably will have problems - with that card anyway. It's unlikely that your power supply would power the 7600GS.
That card requires the following: Minimum of a 350 Watt power supply.
(Minimum recommended power supply with +12 Volt current rating of 18 Amps.)
Open the case and check the label on your power supply. Make sure the power supply meets the recommendations above. Unfortunately, I can guarantee that a HP made in 2001 will not have a power supply adequate for that card. It doesn't hurt to check, however.
Consider building a cheap, budget rig. You can build one for as low as $600. If you've never built one, it's easy.