I don't know how it got there, but theres a purple line going down from like near the top left corner of my moniter. at first i though it was from my wallpaper. But then i played some games and the line was still there. Does anyone know what it is and how to get rid of it? Thank you

You might try a System Restore to a point prior to your problem:

start > All Programs > Accessories > System Tools > System Restore

er. it didnt help. but. for some reason, the purple line is getting smaller and smaller. thats weird. does anyone by any chance know why?

Try Safe Mode and see if it changes.

Safe Mode will only load the basic graphics driver.

Unfortunately the behavior sounds like a faulty monitor to me.

Faulty monitor or graphics card on it's way out.