Just to confirm, since I don't have PSUs lying about, that even though I have power to everthing else (fans, dvd, hd and the green light on the board) it could still be the PSU?
Yes it could be the PSU. I live overseas and usually use 220V versus 110v. I plugged my computer into a transformer that "stepped down" 220v to 110v while leaving the PSU switch to 220. Everything worked, all lights, hard drive, but no boot. So you see, you could be getting power but it's so "low quality" that it's not enough to POST. Just a guess that it's your PSU since yo already checked all the obvious, tightened connectors, etc.
The beeps are important. Radio Shack sells the mobo speakers for about 99 cents, good investment.