|"How memory would be on a used ATI Rage IIc video card"|
The term CARD is frequently mis-used. It's a CARD ONLY if it's on a physical board that plugs into a mboard slot, and that board can be removed. If it's built into the mboard, it's NOT A CARD !
Some older mboards have an ATI Rage IIc video adapter built into the mboard (Rage IIc onboard video) . In that case, the ATI Rage IIc video adapter shares some of the ram that has been installed in the mboard, and the amount shared with the video cannot be used by the operating system. You can often change the amount of memory shared with the video in the mboard's bios Setup - in this case, you would probably set that to the max.
If the ATI Rage IIc video adapter is on a physical board installed in a mboard slot, then the CARD has it's own video memory, that is not shared with the ram that has been installed in the mboard, and all the ram installed in the mboard can be used by the operating system.
As jam has said, the ATI Rage IIc video chipset is OLD - it first came out in or before 1998.
There are lots of programs and web sites that cannot work properly with the meagre amount of of memory that your ATI Rage IIc video adapter can use.
You are much better off installing a video adapter CARD with a newer video chipset, if your mboard has a slot a video card can be installed in.
The drivers / other software support for the ATI Rage IIc video adapter are probably built into XP, and are installed automatically when XP detects the chipset.