Studio 1558 i7 black screen

Hi

I have a dell studio 1558 (i7, 4gb ram) which, since yesterday, has refused to boot. The machine powers up but there is just a black screen.

Here are the symptoms:

-power button light is on, as is the keyboard backlight

-pressing 'D' with the power button flashes up colours

-pressing 'fn' with the power button does nothing, no beeps

-it makes 2 beeps (I think) if I take out both ram modules (just to test)

-HDMI and VGA outputs show nothing

-battery-out power-button-held-in trick worked for a bit, but not anymore

For about a week prior to this it would BSOD sometimes, with a stop code of 0xA0000001, and other numbers in brackets that I can provide if that's important. Then yesterday the dell startup screen was showing but with random blinking coloured pixels. Then it stopped booting altogether.

After reading a few other threads on here it seems like an onboard graphics problem, and the motherboard will need to be replaced - but how can I be sure it's not, say, the CPU?

I've had it for nearly 4 years and it's out of warranty. It tends to run very hot, even with extra fans, and has done since I bought it, so I guess that might've damaged it.

Another question: if I take out the hard disk and send the laptop somewhere for repair will they be able to fix it without? I have large amounts of data on there (hi resolution wav files etc) that I need to access and nowhere to copy it to!

Any help appreciated

Thanks