Those are normally "built in" cards, IIRC, in which case I'd find out from
your system manufacturer if you can uninstall it or not. (Yes, even though
it says "AGP," which is normally a type of slot, a lot of built-in cards use
that.)
You need to know if it's built in or a seperate card anyway before
purchasing a new card. If you have an AGP *slot* (actual, physical place to
plug in an AGP card) you're good to go - uninstall the driver, remove
thecard, plug in a new one (personal preference here being
nVidia-basedcards) per thenew card's instructions, then power up, normally
put in a CD so it can find the driver, and go... It's actually easy to do.
If you *don't* have an actual AGP *slot,* but "built in, integrated AGP
video" (which you'll normally have if its sharing main memory wth the
system,) you'll be stuck looking for a PCI version of a video card. There
are still a good number out there - from both ATI and nVidia (even the
GeForce FX 5200 and, I believe, 5600, from their newest "family" of cards)
but performance won't be as good as an AGP based card. You'll also need to
find out if the onboard video can be disabled - you'll have to talk to your
manufacturer about that.
