> - and, in some cases, specific airflow channels, and a few PCs have this
> need but not usually

I have definatly found that if I leave the case off my machine at home it
will eventually overheat.
I guess 2 processors, 8 hard drives and a voodoo 3500 all build up quite a
bit of heat and with the sides open the heat will tend to just stick around
in the case for a while,  but with the sides on the 4 fans that I have in it
can turn it into a wind tunnel and get the heat out of it.

My guess is that if all you have for fans in your case is the CPU fan and
the power supply fan, you are better off with the lid off your case, but if
you have some extra push/pull fans in your case, you should put the lid back
on so they can do their job.

Brian Cluff