I just answered a question on AllExperts.com where I volunteer my services. This person was asking about all the changes and upgrades of software and drivers since the current scan they did recognized many incompatibilities and they wondered if this was normal and what to expect.
First of all, IF it comes out by January.... yes, you are going to have to perform many software upgrades. I highly suggest NOT doing any change of operating system unless you are ready and willing to deal with many headaches for some time! Even though they have released the beta versions for the general public to try out, I see the biggest problem going to be with the memory itself. This thing is a pig and with less then 1gb of RAM forget about it! Not to mention the many software clients out there that are already scrambling to provide device drivers, etc. Take a look at Windows 64bit edition for example.... now that the processor manufacturers (AMD and Intel) are producing 64 bit cpu's with dual core technology and quad core right around the corner, Microsoft has pretty much ditched their windows x64 for Vista.. as with this, many software vendors STILL have not produced 64 bit device drivers for that, therefore it is quite safe to say those that will be using windows vista will be far and few... I would say the only people to use it will be those buying a new computer with which it will come delivered inside. I think the 'upgrade' rate will be rather slow.. especially since a well maintained windows xp with lots of memory and a fast processor is very fast already, not to mention the software that is currently available, comparable to vista. do yourself a favour, for now, sure go ahead and read up on this new O/S and see just what things you will be looking at having to do.. in my opinion, the best thing you will do is simply go out and buy a new/cheap computer with Vista on it.. since you can already buy a bare bones computer for under $300 (that includes the operating system), doling out $150 or more for a new o/s seems pointless.
Obviously as time draws near to the supposed release of this, I am sure I will be answering many more questions on this topic. Hopefully with the public release and all the technical reports so far, people will NOT be in such a hurry for a change of O/S just because they are currently bored with XP! But I am sure my TIPS page will soon be filled with solutions!