I went on this subjet a while ago..
And I made up a software raid array of two old disks within windows ... not bad at all, but with time going on.. it seems to slow itself down...
When I made thie raid array up .; Sathrah was wonderfull.. no lag, no pain, no alt loosing its follow ... but after a while, I have now those hangs again ...
my thread about this : A Raid array of Disk images volumes

I really miss a Quad CPU.. at leat that's my though