Just thought I'd chime in and say that I had an original Intellimouse Explorer, and it lost power (the cord was broken or something).  I called MS, and they shipped me a new one...easy as that...well, kinda.  They were out of stock of the mice and said it would a 4-6 weeks.  The mouse shipped a week later.
Okay...that was boring... here's the cool part.  Since you don't have to ship the old mouse back, I opened it up, cut the cord, stripped the wires, etc. and soldered it back together.  Works perfectly.  So, I basically got a new mouse for free!  Well, the first was a gift, so it was free too, but that's beside the point...  Anyway, as much as we all dislike Microsoft's software practices, their hardware replacement program is first rate.  I wonder if my new mouse will break...then I'll get a third!
Squibby