Intel P4 2.4
ATI 9800 Pro (XT Chipset)
1Gb RAM

Settings 1024x768 all on Medium except Grass I think, changed from the preset graphics settings nothing as I think it looks fine :) may have a play around.

I have some slight lagging at certain view points on both the campaign but if I move the camera slightly its fine and doesn't seem to occur when I move back to a similar view point.