Did i destroy my power supply?

I have a compaq presario sr2175x desktop and have modified it a little with a new graphics card, ram, and just installed a 400 gb sata from western digital. well i installed the new hd and powered up the pc. could not get the pc to recognize the sata drive. had the pc on for a while trying to get it recognized and never did get it recognized. i powered off the pc and was going to go into bios to check it out to see if the settings needed adjusted to get the drive recognized in my windows vista os. cpu powered off and when i hit the switch to turn it back on, nothing!! pulled the power plug out of the back and waited for a little while and still nothing when i tried to power on. the little green light on the back is on when the plug is in, but i don't know if my power supply has gone bad or what. if i do have to buy a new one i think i will prob get a better psu that can handle more. can anyone help me and tell me if this is hopefully a psu problem or maybe (hopefully) another problem that i can fix.

Probably did... It wasn't the SATA drive, but the video card... we replace Compaq Presairo power supplies all the time... measure the one you have in millimeters of length, width, and height... then buy the most powerful one of that size you can afford in ATX v2.00 format on up to V2.03. You will do fine with an Antec, Seasonic, FSP Group, Sparkle... that is 400 watts or more. Just don't go too cheap in price.