When you mention the thermal pad on the heatsink, which are you referring to? I'm guessing the blue "pad" thing that sits on the north bridge chip?
If so, a little dust on it doesn't seem like it should be a huge issue. There shouldn't be any in the center part that actually mates to the chip since it's been in contact with the chip all along. If there IS some notable dust in the center, that MIGHT be a concern, but I'm not sure how much. The thermal pad in my DV9700 actually has two small gouges in it and has been pried and replaced dozens of times and still works fine. If the dust is along the edges, it should be fine.
Dust is really only a problem when it's directly between a chip and the surface it's supposed to be touching.
O Shadow Fox O
Edit: Just looking back at your pictures, it seems like you have an integrated GPU (there is an empty square to the left of your north bridge in the pictures). Dust in the center of the blue pad would be MORE of a concern that way, but again unless it's a decent amount (or it's just on the edges of the pad) you may not have much to worry about.
Yes, I was referring to the blue pad.
There actually is dust in the center. I've reassembled and disassembled it many times due to it over-heating and now I'm thinking of buying IC7 Diamond and the used heatsink and fan I mentioned earlier. I can't seem to get it right especially since it's a pain to keep taking it apart. Now I think there might even be a scratch towards the top of the heatsink due to improper cleaning I believe.
I took it apart again and did some more researching on how much compound should really be added, and I saw that it should only be a thin layer which I added little drops a couple times to make sure it was covered nicely, but I believe I did it wrong. I added a layer onto the heatsink and on the GPU as well. I've seen people not add compound to the GPU at all, only the heatsink and tend to get away with it. I'm wondering if I should do that since I have trouble adding the compound correctly right now.
I reapplied the paste multiple times, which I'm not sure if im doing it right or wrong or im just using the wrong paste, and it's still over-heating. I'm pretty much looking to buy a new PC since I've had this one for about 4-5 years I think? But yeah.. it's getting really annoying that it keeps over-heating and it's a pain to keep taking it apart!!