Optimizing a PIII 550mhz 300 PL for video capture

I've been experimenting with a WinTV capture card, but having somewhat
unsatisfactory results in capturing video. It seems no matter what
format, capture dimensions, keyframe rate etc. the video playback will
have hitches in it. I don't know if the problem is the capture card or
my system.

I'll be using a Pinnacle DC10 video capture card and Pinnacle Studio 7
editing software. What are some steps I can take to optimize this IBM
PIII for video capture/editing? Possibly in the bios? At the outset at
least, will be transferring analog 8mm and VHS video. Are there any
particular "bottlenecks" with this particular system that might cause
problems?

Running Win98 first edition, 384 megs ram, capturing to a brand new 60
gig Western Dig. ata 100 7200 rpm drive.

Thanks for your input.