Monitor switches off and on then shows no signal

My desktop is having display probs - the screen was occassionally going black then picture came back but now its clicking off and on then going to standby with msg no signal detected. have tried a different lcd and get same error. Does this mean my graphics card is goosed - I do see bios when it boots up and then see the windows xp screen before the screen goes to standby? Any thoughts on what I can try appreciated - dont want to mess about too much or open up if this is an easy fix!

Will give that a try as its been sitting doing nothing for about 6 months! ANd might even open her up too and see if anything looks like its slack or shouldnt be somewhere but will be later as have to hit the sack as its nearly 2 am in UK and have 2 toddlers and no-one else who will get up for them! Thanks so far!