That number was for a 512 MB card, but with 256 MB the operating system will see even more ram.

The maximum amount of ram that 32-bit XP can recognize is 4 GB minus whatever is on the video card (minus a little more). Therefore with a 256 MB video card, the maximum will be a little less than 3.75 GB.

Bottom line: if you get 3 GB of ram, the OS will recognize 3 GB. If you get 4 GB, the OS will recognize a little less than 3.75 GB.