My sister's PC went up in a similar vein to this. When I opened the PC, I
found that ram had actually caught fire and singed the simm sockets. To
check if this has happened to you, and if it has, I am sorry, because there
is almost nothing you can salvage from it. Look at hard drives and cd rom /
dvd rom, check for any chips that have cracks, or bits blown out of them.
even graphics card and ram can possibly have parts physically blown apart. I
theorize that her power supply's +5 volt rail was driven high maybe to
around 40 volts and blew everything to pieces.

Paul