did you manage to get a new psu?
try this test: unplug all extra devices so you only have the 1 hdd, 1 optical drive, mobo/cpu/ram and video/audio set to onboard if possible.. boot up and see how long it takes (dont install the onboard drivers if you still plan to use your external audio/video cards.. less problems..)
if it boots normaly, then power is your consern.
other than that, if it still lags, then its time to go into detail on your hardware. inspect your motherboard for any stains, smells, unnatural looking components - especialy capacitors blown, etc.. and start swapping stuff like IDE cables, jumper cables (if used), power splitter/connectors etc.... run memtest on your ram, as well as a hdd diagnostic program from your hdd manufacturer's website.