cleaning a laptop

I do all I can to keep my laptop clean but it's mostly an external operation. Keeping the keyboard and palmrest and all wiped and in the case of the keyboard and any ventilation openings vacumed or blasted with air. But it's lived three years in a less than pristine ,construction office, environment and has to have dust collected deep inside, where it's hard to get to. Is it possible, or recommended to take out all those screws and separate the case to get at the deep innards? I'm sure the place must be pretty dirty and can't think of any other way to really really clean it out. If I go ahead and dissasemble it is there anything in particular to be extra cautious about? I've never seen the guts of a laptop and don't have any idea what alls in there or how it's configured, but the fan area, which is inaccessable from outside the case has to be dirty. I am looking for any advice at all here, because I'm going to do it anyway and could use any pointers you might provide.