[V8] AC Compressor Clutch--Imminent Failure?

[Gunter Lorberg]

I drove my car 300 miles yesterday....stereo on and windows up.  When I finally pulled into my garage and opened the door (engine still running), I heard a load screeching noise...I don't know how long it had been there but it was not loud enough to drown out the stereo while driving and there were no performance issues.  I had been driving with no AC and decided to turn it on in the garage (as a test) which caused the noise to go away.....compressor kicked in just fine........turned it off....the horrible noise returned...
 
With the car cold today, I just went to start it and noise was not there....AC could be switched on and off without any concerning sounds...it wasn't silent mind you
 
Anyone care to guess what is going on?  How long before my AC clutch completely packs it in?  Can I drive this car long-distances worry-free (with the AC on I suppose?)?  What needs replacing?  The car has about 165 000 miles on it.
 
Thanks,
Gunter
(2) Canadian '90 V8s