I can only agree with Swash here. The only two laptops I've seen survive past their fourth year are my own (replaced the HDD twice, split the entire thing apart twice as well to give it a cleaning to prevent heat problems) and my ex's (fucking miracle).
If you only hit boot, never windows, it's most likely the HDD. If you don't get any response, it'll be the I/O controller, the keyboard and/or other bits and bobs of the hardware that're fried. Problem with this sort of error is a) laptops being ridiculously hard to find errors on (because you cannot simply replace hardware until you find the arrant bit like we do on desktops) and b) laptops suck at having proper output controllers and beep-devices to tell us error-codes. If I were you, I'd give the geek-squad a try, see what happens and most likely go order a new laptop when they declare the poor thing DoA.
