the long release time between xp and vista has put ms in a pretty precarious position with regards to user retention. since a lot of normal people wait to buy their computers until it comes pre-loaded with a new operating system, there are a lot of pretty old pc's out there right now. these folks have been waiting for vista for a while and are likely getting pretty tired of their current computer setups. in the meantime, mac os x has been getting good press here and there and many of those same people have broken their apple "cherry" with the ipod and itunes.
if apple can time the release of leopard fairly close to the release of vista, they could make a pretty serious maneuver that would strike right into the middle of the windows userbase. they could release tiger for generic x86 machines for a very low price (say $50). the people who want the latest and greatest of apple's operating system would still be buying macs and apple would still be enjoying their margins.
the people who are getting frustrated with their xp systems could either 1) buy vista for a fairly hefty sum, 2) buy a new computer with vista pre-loaded for a heftier sum or 3) buy mac os x 10.4 for a small fee just to see what it's like. if tiger works better on their aging hardware than xp did then apple makes microsoft look foolish. if it works just as well as vista, then microsoft looks pitiful. all of the r&d for tiger has already been covered and releasing it for other x86 computers would be pure profit (other than the expense of adding in some more drivers). users have nothing to lose by dropping $50 on their old computers to see if they could get more life out of them. apple has a lot to gain and could minimize the threat to their hardware margins.
there might even be people who would be willing to try it and still buy a new machine, in this case a new macintosh. even if they don't buy a new machine now, apple could gain a lot of markshare when the next wave of computer upgraders come through.
microsoft would likely try to hit apple where it hurts, which is microsoft office for mac. but since macs run on intel chips now and they're obviously amenable to the idea of running things in a virtualized environment, the loss of office for the mac platform isn't nearly as scary as it once was. if they let windows applications run natively in the os x environment, then microsoft basically can't stop developing microsoft office for macs because they could just run the windows version.
what do you think? does this theory make any sense? seems like the least dangerous way to convert a lot of people all at once. sure they might lose a little on hardware sales to people who would buy a dell and run the previous generation of os. but it would likely be offset because even if only a fraction of those switchers buy machines from apple they get a big chunk of profit from them. if 10 of 100 people who use this "generic" version of os x buy a mac next time, they probably more tha make up for the cheap folks who would be willing to run an old system to save on the hardware costs.