Relationship between AGP Processor and mother board processor

I never tried it, but i think your old pIII have a agp x4 port, that would be ok for "newer" graphic cards with something like a NVIDIA GeForce 7600GT.

System Requirements for the card above are like this:

* Intel Pentium III, AMD Duron or Athlon class processor or higher

• 256MB system RAM

• A minimum 350W / 400W recommended power supply

• PC with one free 4x or 8x AGP graphics slot available on the motherboard with full size expension slot

• 50MB of available hard disk space

• CD-ROM or DVD-ROM drive to load the driver or download it online.

• DVI or VGA compatible monitor

• Support for Windows 2000/XP/Vista/Windows 7 or above system

so check whats inside your computer and if you want a specific card - check if there are drivers for your operating system available