No Video on BootUp in Dell Vostro 1500

Hi,

I have a Vostro 1500 laptop, about 5 years old. Suddenly yesterday when I started the laptop, nothing appeared on the screen.   Only a faint glow (Backlight of the LCD) was visible. In the background it seemed as if the booting was going on... After few minutes some light gray vertical lines started appearing on the dark background. to restart, I had to press the power button for more than 5 secs.

Other observations,

1. I ran a diagnostics test by pressing the Fn Key while pressing the power button for starting the Laptop:
Same dark screen was visible for some time (round about a minute). later the screen was displaying different colours white, red, green, blue. this repeated once more time and then some diagnostic beeps were audible.

2. I tried connection an external LCD monitor to the video out:
This i did by pressing the Fn + F8 during the bootup process. after this the laptop lcd screed went completely black (as if switched off), On the external screen, i could see the windows progress bar and the word 'windows', but with some blue dotted vertical lines across the screen. Once the progress bar was done, the only video was of the vertical dotted lines.
Afterwards nothing...

to me it looks like a graphics card problem... any ideas..? and how to solve this..?

Regards,

Rahul.