where as a pentium4 will kick nearly any cpu's arse at video encoding, due to long pipelines and no need for prediciton
An AMD 64 whoops its arse on games.
depending on the speeds,a pentium 4 will probably eb quicker than your athlon 2400+
run a benchmarking prog
or dp what i did last year, buy a xp2500+ with barton core, whap the fsb up to 400mhz and there u go super fast 2.2ghz amd with 400 mhz fsb on the cheap