I think it's too early to be too concerned. The economy has no doubt kept people from upgrading what is for most a discretionary piece of software - especially if it would entail a hardware upgrade as well. There's also the XP factor. At some point, things are 'good enough' for many people that they will jump off the upgrade treadmill for a while. 

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken