when i first started playing live i used to use my pc running sonic foundry vegas to play the full audio file of each track that id wrote in orion...each wav file would then be arranged into a set with all the edits, fades, twiddly bits pre programed...this left me to play my synths or trigger samples over the top...with a little dj style eqing it didnt sound bad...and was pretty fail safe, but now i use a pc with a tascam u122 external usb card and cubase vst midi synced up to my korg esx1 sampler(which i use for drums....with the hi and low parts seperated and eqed through my mackie mixer) then cubase is used to put the set together using vstis (Audiorealism bassline (top 303's!!!),junox,minimoog,arp,slayer etc) and other plugins...i have an oxy8 midi controller for playing riffs on and i have no problems using this set up...unless the pc decides to be a bugger and crash of course!!!
...touch tonnes of wood that this doesnt happen!!!!