my computer is dying - the saga continues.

when i try to play dvds there is a lot of weird green spots on the screen, kind of like it's not reading all the coding off the disc. do i wait until it goes completely kaput or do i just go ahead and buy a new mac and transfer everything then send this one to a computer graveyard/part salvage place?

i know that i can't afford a new one, but how in the hell does one live without a computer? i did that in college and it completely sucked until i got my little gem of a mac for christmas one year. however, times were easier then because i had access to computer labs all over campus. blah! i seriously don't know what to do.