Help. Playback hicups periodically. please

[potential]

I'm on beyond tv trial.
everything works fine.

I can record fine even at "best" settings.
Playback seems to be fine even at "best" settings. but it hicupps periodically, say, every 10-20 minutes. i lowered the record settings and it still hicupps. (hicup as in stops for about 1 second then continues to play).

but when i exit and play it with windows media player, no hicups.

i'm using nvidia decoder-software.
Can Xcard solve my playback problem?
Pleaes don't say buy a P4 system!
My machine is going to be dedicated PVR machine.

Anybody know if SageTV software with pvr350 can solve my playback issues. I would have 2 happauge cards at the end which is fine. hopefully i'll be able to record 2 shows at once or watch something else while Sagetv records.

currently have:
PIII 600 w/512 ram, pvr 250, 250gig
i consider my machine a toaster. but like what the add says, i should be able to turn my toaster into mean PVR machine .