Ive now upgraded my PC system and am managing to capture and DivX in realtime.
Now using an Athlon 1.2GHz on a Gigabyte 7IXE4 mobo with an IBM 40gb 7200rpm IDE hard drive.
Settings as follows:
smooth -> crisp : 50
data rate: 4000
audio captured as raw 44.1khz 16bit stereo
CPU usage stays around 40% and only spikes sometimes.
It kicks ass!