If this were only for digital video capture would get the DC10 unless I had a powerful enough computer and fast enough hard drives to mannage the software based encoding that comes along with the AIW radeon 7500. (I don't think your Athlon 800 is powerful enough to capture at the highest settings) I had a DC10 in my possesion for a short time (I borrowed from a friend until I scored a Fast AV at an MIT swapfest.) The DC10 had pretty good Capture quality (check the hardware opinions you'll have some people who love it. ) The only caveat I could think that would come of it was that pinnicle did no update the drivers to run on Windows 2000 and for that matter windows XP. If your gonna use the DC10 you'd need to either run WIn98 or Linux (I know it has driver support I just don't remember the chipset)
As for the radeon AIW 7500, I've heard you can get decent capture with it if you use can get it to work with Virtual Dub and huffyuv, I myself owned a PCI AIW radeon and for the life of me was never able to get it to capture in Vdub no matter how I tried) I don't have much to say about the software mpeg codecs that came with it as I was unable to get much quality out of that card because my PIII 667 mhz computer wasn't up to the task of encoding at the highest standards.
Take that as you willl.