Need Recommendations for Video Adapters for Dell 4700, GX270 & GX280 PCs

Hi, we're are using Dell 4700, gx-270 & gx-280 PCs w/ onboard motherboard
video
and Dell LCD displays. We're using Google 3D Earth maps and are not
satisfied with the video performance
and are looking to upgrade to using video adapters. Would like some
recommendations
for some good quality video adapters that'll run Google Earth maps smoothly.

Thanks,

Mike