What processor u thinking of going for, you have a choice of the following higher end CPUs with that mobo:
AMD Athlon™ XP 3000+ (333 FSB)
AMD Athlon™ XP 2800+ (333 FSB)
AMD Athlon™ XP 2700+ (333 FSB)
AMD Athlon™ XP 2600+ (333 FSB) Model 8
AMD Athlon™ XP 2600+ (266 FSB)
AMD Athlon™ XP 2500+ (333 FSB)
AMD Athlon™ XP 2400+ (266 FSB)
Go for the for upper end of that list
. This link i a bit out of date now, but gives an idea of video editing perfomance of CPUs:
http://www.tomshardware.com/cpu/2003...charts-26.html
Finally, if I were you (a bit of a newbie with stacks of analogue video), I'd spend the money on a dedicated anologue converter like the ADVC50. And you also won't have the restriction of choosing a graphics card with VIVO - but go for one with the best preformance/value!