Mitsubishi Lancer GLi 2000 Manual?

Hi, I have a 2000 Lancer GLi 1.4L Manual with approx. 170,000kms. When I accelerate a squeaking noise appears, whether it be coming from the engine or the timing belt I don't know. It goes away when I lift off the accelerator, but becomes louder the faster I go. For example, I do 100kms p/h along the highway and it is at it's loudest when I slightly hit the accelerator. I've started to notice a rattling noise along with it too.
If you have any ideas to what it might be, even if it's a guess, it'd be very much appreciated so I can get it fixed. Thankyou :)

Rachael
May 2009