Well after trying everything I could think of I think it was the integrated graphics card as the machine wouldn't output to an external monitor or go past POST by the sound of it.
In the end I replaced it with a Samsung S3520 from PCWorld which was the best deal I could find for a laptop with these specs.
http://www.pcworld.co.uk/gbuk/samsun...83827-pdt.html
Cost me £450 after cashback so not too bad.
An expense I could have one without but the new laptop is very shiny and fast so not all bad.
I can't believe how cool it runs too compared with the old Sony!
Thanks for the advice guys