If is not the HDD nor Vc nor memory stick it could 2 more stuff ( Or 3 at the worst ) a dead mobo, a dead cpu or a "Semi" dead PSU ( i bet is the mobo )
Try to look if any of the capacitor of the mobo are "inflated", Sniff aroud the mobo and try to smell if there is something "burned"
Try without the HDD and see if boot ( At least till the D.O.S say that you need a HDD =P )
Or, do you have any kind of CD-Live of linux that you can load on the fly and see if still hang up your system?
So we can "Discard" that is a HDD problem, but in general talking that kind of "Fan spining" and no signal of the monito is related to memory or video problem
Also, check if the speaker of the case is connected to the mobo, so you can "hear" the beeps
90% of the pc have at least 1 beep when you hit power that beep means that the system is OK