Battlefield 2 hits your onboard GPU's memory hard. In some cases, the game uses over 256mb of memory. Here are benchmarks going from a 128MB AGP Aperture to 256MB AGP Aperture within the BIOS:

128 AGP
Time (ms), Min, Max, Avg
60000, 25, 97, 73.783

256 AGP
Time (ms), Min, Max, Avg
60000, 39, 97, 76.417

(Max quality @ 1280x1024)

Gamers may want to change their AGP aperture size from within their BIOS!