NeedaComputer

My hard drive went out on me and I was able to get some of the files off of it before it wouldn't allow me to boot using it anymore.
My next step I tried was after it booted, (OS on a different hard drive) I would plug the Molex into the bad HDD (data cable was SATA) and the computer recognized some of the partitions and I was able to get a few more files. After trying that a few times, (I would get an error supposedly from not being able to write to the bad hd) I would have to restart. Then the last time I hadn't even plugged in the HDD and everything shut down and I've got no power or anything.
Could there be a simple fix like replacing a fuse inside the PSU, or am I looking at a new one? Thanks for the help!

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AMD Athlon64 3500+ Orleans
MSI K9N Neo (MS-7260 - nForce 550)
Corsair XMS2-DHX DDR2 800mhz (4x1GB)(4-4-4-12-2T)
MSI GeForce 6600 - 256MB 128bit
XClio 450BL
WD Caviar SE16 - 250GB 16MB 7200RPM 3GB/s
WD Caviar SE16 - 500GB 16MB 7200RPM 3GB/s