Ouch! That's a lot of work just to have that happen, Alan.
I used to use the Hauppauge WinTV card for captures, but had the same problem. It was caused by 'dropped frames' because my PC was not fast enough to keep up with the massive amount of data flowing to the hard drive. I worked very hard to streamline my PC and made some improvements, but not enough. The only thing that worked was cutting down the screen size of the video capture. I ended up setting to 352x240 and used the Brooktree lossless compressor. That let me capture without a sync problem, but the video quality wasn't that great. Then I ran into the Win98 Fat32 4G file size limit, which was good for just a few minutes of video. Using XviD one-pass compression let me get a couple of hours into that 4G file, but then I couldn't do hardly any post editing without horrible re-compression artifacts ruining everything. Very frustrating.
About 18 months ago, I took out the WinTV card and got a Hauppauge PVR-250. Much better! I can capture at 720x480 (720x588 for PAL) direct to DVD compliant MPEG-2 with much smaller file sizes and never a sync/dropped frame problem. And it makes conversion to DVD much faster. Post editing can still be a problem, if multiple recompressions are used, but with a proper 'cuts only' editor even that can be avoided. The PVR-250 is well worth the extra cost.
Fav quote - "Experience is whatcha don't get 'till ya don't need it no more."
System - Athlon 1.4GHz, Win98, Hauppauge PVR250 receiver and compressor.
Software -Magix Movie Edit Pro 10, Nero 6 + NeroVision Express, Moho 4.61, PSP 8.1, Bryce, Quicktime 6.52 pro, Goldwave 5, DVD-Lab.
Cameras - Panasonic GS9, Canon ES8400V, Canon EOS D20 and Canon A70