Ooo, ouch. I tend to do a "wipe and re-load" of windows every 6-9 months. I guess it's a habit from the old days when Windows was, shall we say, less stable. I haven't run into any max activation issues yet, but then again, I have only had to do one re-install on my laptop lately when I took a Linux distro off and re-sized the partitions. (All these great new skins coming out lately take up soooo much room!)
I think that at some point they must reset the number, or limit it to 5 within a certain time-period. Other comapnies have done the same thing. I can remember the Plus! pack doing the same thing. I had bought a license and was doing wipe and reloads several times over the course of the year, I just had to call in to Microsoft and the had reset it. (See - it does pay to register your software occasionaly)
So, after a long ramble, I guess I would like some clarification on this as well. Haven't run into it as of yet, and had OD for a few years now, but I know that I will have to get a new machine at some point, and if my Office 2007, Vista and Windows Mobile 5 don't start playing nicely soon I'm going to have to wipe and reload again at some point!