Linux left Windows as first choice for boot-up on both my machines, it's really annoying

The thing is with Linux there is no need to shut the computer down overnight, in fact I believe it can be left running for years with no ill effects.
It's hard to explain, but it runs nothing like windows and goes into an auto sleep when left.
Things I have noticed, my laptop was always noisy, mainly the HD ran full pelt constantly, now I can't remember the last time I heard it? It must be running?
Or maybe it's the fan I used to hear? Dunno.
Secondly with Vista if I put my hand over the fan vent the air coming out was hot, and I mean hot, certainly hot enough to keep your cuppa warm on a cold day. On a hot summers day I used to get worried about just how hot my laptop was getting, even the keys were warm.
Now the air vent temp is barely noticeable above room temp....
If I look in System monitor I find the memory used is 22% (Vista 90-100) swap file 0% (can't remember?) CPU1 34% CPU2 27% (70-100 for both almost all the time)
This laptop has now been on for 3 days con't, if I were running Vista I would have forced at least one if not two re-boots per day to clear the memory as the machine got slower and slower.
One thing for sure, my laptop will last a lot longer under Linux, no doubt about that.
And my electric bill will also thank me...