about a year old - still was working hunky dory til i got a message a couple of bootups ago telling me that there was a 'suspected fault/integrity issue' for the hard drive, or somesuch (sorry, didn't note it down) - this msg was on the bios/bootup screen. i rebooted as it advised a full harddrive backup. got into windows, started getting my stuff together to backup and the computer just went dead.
since then - i get a quick blue light when i start up, but only ever if i,ve unplugged at the mains and reconnected again. thought it would be a power issue so bought a new power supply. still nothing.
try unplugging the video card and plugging back in. If this fails to do the trick I assume you are not getting any beeps. Make sure all usb devices are unplugged I spent several hours trying to find a non existing fault and by chance removed a usb cable and the pc fired up.