SPCR

I have an 2 or 3 years old Compaq N800V notebook with an 1,9 processor that gets really hot. I've opened it and cleaned it from dust and it didn't help much.

Does any one know if they use thermalpads on the CPU and do you think that I might gain something by removing and cleaning their heatpipe-heatsink and apply some fresh as5 on it?

It's probably worth a try - it might make a couple of degrees difference.
Thermal pads are quite popular with OEMs because they're easy to use, but I don't know if they're used in the n800v, having never taken the CPU out of one.

Laptops can be pretty tricky to improve. You could consider one of those cooling tray things that sit under your laptop, blowing cool air into it.