Does your monitor have 5 diffrent plugs in the back for the video? I used to have one and the red plug would come out all the time and the screen showed no red. Check your cables.
Yeah very smart check those pins. Do you have any other monitors in your house you can hook your computer to or at a friends house? So you can diagnose this problem to your computer or monitor? If it is your monitor witch i believe, you can get a 17 Inch CRT monitor with good resolution for under 150$ brand new. If you have to or want to replace it here is a great link for some good crt monitors. Member CRT monitors are better then LCD.
hmm my brother got a dell notebook off ebay, one of the colors didnt work (i think red) and they had to send it to Dell, but that was a notebook and you said youve had yours for awhile.