System specs

900mhz AMD TB
348 megs of ram
WIN XP
5400rpm 40gig HDD

When i try and capture in mpeg 1 it loses 50 percent of frames. I cannot capture over 320x240 in VDUB or I lose frames. I was under the impression that this card could capture at high resolutions higher than that without frame loss on a 700mhz pc - and mine is 900mhz

Also the 320x240 capture at 6000bits/sec dont look as good as the ones I did on my WINTV GO card
any suggestions?