Bad power supply

Im pretty sure my power supply is bad i just want see if there is
anything else that may be the problem. I have an an antec sl350
and 2 days ago pc crashed and wouldnt start again. It happened before but always came back on after a while,not this time though. I took out everything and changed the vid card and still no go. I then put the psu in another comp and it would boot but
i kept getting boot disk failure, they went away when i put the origional psu in.So is there any suggestions or is it definitely the
psu.

Abit SA7 mobo
Pentium 4 2.4ghz
2 256mb corsair ddr ram
40 gig western digital hd
Geforce 4 128mb ti 4200
Altec sl350 psu

In all my experiences, problems like that are either due to RAM or the PSU 95% of the time. So, if the PSU messed up in the second system, then I'd say it was the PSU. Did you try using the PSU in your second system for your other?

NO didnt try the working psu its not compatible with P4 motherboards.