I have an ASUS G51VX that I've had for about 5 years and it ran fine, except when watching HD videos; then it had a tendency to overheat and turn off. I took the heat sync off to apply some Arctic MX-2 Thermal Compound; I also found a fair bit of dust was clogging the fins that come out the side of the laptop, I did away with this using some Kensington Dust Guardian, which turns the dust into a substance of a muddy consistency.
When I pulled the heat sink off, the thermal pads on two of the RAM Chips on the CPU ripped and I'm wondering if I need new thermal pads now; I mean they could just mush back together when the chips heat up, but I'm not certain if this will be the case, so I was wondering if I needed new thermal pads and which ones would the the appropriate ones for the job.

You can see them just towards the bottom of the image.