PCs undoubtedly get slower over time. OSx is way better in that respect but based on the data collected in our office Ubuntu kicks the ass of both OSx and Windows. Those using Ubuntu here have suffered no slow down in two years. I guess that this selling point will ring very true with consumers. I also imagine that google will continue to autoupdate (for free) the OS and, being Linux based, it is more likely to work just as well in 2 years (as our Ubuntu installs).