I have had my macbook since 2008. It is OS X.
When I try to turn it on, all it does is 3 consecutive beeps, then waits a few seconds, and then beeps again. It does this continuously. Is it time to get a new one?
Any help would be much appreciated, as I have some important notes on there.

The problem is most likely the RAM of the computer. Very cheap to replace.
Take it to a PC service center for them replace and test it.