MAC. Servicing my own.

for some time now, my MAC mini -G4/10.4- was running at 108F (42C) to 112F (istat on taskbar) when standing still (vs to compiling fink stuff). The last time I used my putty knife was to install non-apple store, memory for expansion, like a year +1/2 ago.
I looked at it, and the dust (muck) all around the inlet and outlets was building high. So I took my putty knife again, opened it up, and used the blower for a good 3-4 minutes. Plugged it in (the wires) and now is working again at 38C - 41C with some load.
The question is: does this violate any service standards set by Apple? Will they ever service my system (if ever needed)? Do I ever wonna service this system if it fails?
The thing is, that I know people that own mac's, that have never done any trivial service on their systems, for the simple reason that they are artists, liberal arts majors etc, dont know if their system is overheating or any other parameter. Last week a designer ask me why was the blower was constantly running on his system. Hint - Hint !
Mine was crashing like windows millennium for the past month, and had to boot with the install dvd, to run disk doctor to do the "minor repairs required" on this system disk. How many Apples (like mac users) do that. Do we have any sorrow apples? Do they buy the new and approved (h/w+s/w)? since the one they got, failed "cause of age !". Whats the lifespan of a mac? 2-3years ?!

I might be too picky. That also got me a lenovo thinkpad last month. Hasnt installed anything on it yet but the OS! is like I havent figured out of its future (linux server, ubuntu laptop, win7 training platform, virtualbox host or all of the above).

I got 5 laptops, 1 netbook, 2 desktops and mac. dont want to buy anything for the next 5 years (including licenses and software). Is that a plausible future?

all my question are rhetorical, just food for thought. I might sound like a "hippie" minus the hallucinogenics for living 30 years with computers. I believe that marketing has tripped badly over me.

The boldly go... everywhere! but avoid dark alleys, ignore dropped soap bars, bungee, obscure looking meals and "wise" women.

UPDATE: just bought an overpriced [like the one at the link] netbook cooler for 16€ inc VAT, raised it with 4 useless ram ICs -from the 80's era,  cause its too low for airflow- and now my hd temp is in limbo of 39 degC to 40 degC and the weather is hot!! Used to go up to 47C with this weather. The cooler -extra bonus- has blue LEDs too, and the whole system looks like its hovering on my desk.
Gotta kill the lights, my wife and kids are laughing at it. But it works.