Im on my third AMD chip now.. from 1ghz, to 1.33ghz, to the 1900+... Ive probably switced hsfs on them more than a few dozen times while cleaning out the heatsinks (I smoke, and keep an open case) and never had a problem.
I do have a semi related story that I still laugh about to this day. Back when I was doing computer tech work, during the race to hit 1ghz first... The very first day the 1ghz Athlons hit retail, a guy came in asking why his pc didnt work.. He had just gotten the 1ghz chip and was pretty upset that he couldnt get his system to work.
Soon as he set it on the table I could smell burning... So, I checked to see that the fan was plugged in on the Heatsink, and then turned it on... it was on for maybe a few seconds when I noticed that smoke was coming out of the cpu socket.... So, I turned it off, and took off the heatsink, and low and behold... This clown didnt take off the sticker that covers the thermal compound on his heatsink.
I tried hard not to laugh, but I just couldnt help myself... Needless to say the guy was pretty pissed off. Didnt even get to use his new chip for 5 minutes before he burnt it right out.
AthlonXP1900+@2100+, Abit KR7A-Raid, Radeon 9700 Pro (core370/mem666), 256Megs PC2100, 2x 40gig WD7200, Soundblaster Audigy Platinum, KDS VS 19" CRT, Klipsch ProMedia 5.1s, Creative 12x DVD, TDK 24x CDRW, 500Watt PSU, Win2kSP3.