Multiple / New PC's a catalyst for migration to web based apps?

An interesting post on Download squad today that show’s how hard it is (or how easy we want it to be depending on your perspective) to move apps from one machine to another. With the coming Vista wave, is Microsoft creating their own worst nightmare? Will fewer people add Microsoft apps to their new Vista PC because it’s so much easier to use web based applications? This combined with the trend towards using multiple PCs and virtualization will make it very interesting for ISVs over the next few years.
Of course, Microsoft has the advantage of extremely wide distribution, but what about everyone else? If the user has the choice between a web based app to read PDFs that requires no install and works the same on all their machines (regardless of location or OS) or a client app that has to be installed, licensed and activated on each machine, which will the majority choose?
ActiveWords – The most useful utility I’m no longer using – Download Squad