I just felt I had to comment...
The "I hate Microsoft" zealots need to really stop and think how silly they sound, and the "Linux never has any problems" crowd are sadly deluded.
I have Vista HP 64bit installed on my media centre, it has not blue-screened or crashed once in several months, I sleep and resume a lot, it's stable and it looks much better than XP. Yes it uses more RAM, but at <£25 per GB for DDR2 - am I bovvered? The only issues have been poor Creative driver support for my X-Fi (they work at a basic level but the applications are not Vista compatible), everything else has been fine, Nokia software, Bluetooth, TV Card, Intel chipset etc all had drivers and installed fine and are working a charm.
I have seen several other Vista machines and they have similarly worked fine, including the installation of *some* older software. But to be quite honest I don't expect all old software to always work on the newest OS, that'd be what new versions of software are for - to support the new OS and the new hardware etc etc. We all had these problems moving from DOS based 98/ME into 2000/XP - I remember everyone moaning like big girls about their old games not working.
If you're software is not Vista compatible then DON'T BUY VISTA - it's that easy!!! You're not forced to buy Vista at all, most companies will have a XP volume disk around, and I bet most of you private users have a cracked copy of XP. It's still available in retail if you are building a new PC... If you have legacy software, or old hardware, then stick to running the OS on which it was designed to run. I see so many people saying "I upgraded to Vista and now everything doesn't work" - did you even bother to check if it would before you started? It is OEM hardware manufacturers who choose to supply Vista not XP on packaged PCs, they have the option to provide XP (as some do, i.e. Dell if you buy from the business section), but most consumers are not educated and just want whatever the marketing men have told them is best between part 2 and 3 of X-Factor on Saturday night - which at the moment is Vista.
Now onto Linux, yes it's a fantastic piece of software considering it is free, but it is not without it's own issues... firstly the latest distros when installed in FULL (including window manager) are often as memory hogging as Windows, and won't run on older hardware either. Linux also has many quirks, and plenty of forums with people saying "package X doesn't work now I upgraded my kernel/libc/xxx" etc etc - there are all the same upgrade issues as Vista and "this won't work if you don't have kernel version X or better" problems.
(Incidentally before you dismiss me as a n00b, yes you, I know you are doing it now, then I run Linux on about 10 servers, Debian, Redhat based and more, an office full of XP workstations, Vista at home along with more Debian and XP, and some other Linux's for firewalls, have worked supporting OS-X etc as well.)
Bottom line: don't just expect old hardware to run new software, don't expect old software to run on your new OS - and don't blame the OS maker, blame the makers of the driverless hardware or unpatched software. Microsoft and Linux distributers provide an OS - it is up to YOU to make sure it suits your needs and works with your existing software and hardware. They aren't your carer, and if you don't have the personal expertise then that is what your local PC expert is paid for... again not MS fault you don't have the expertise.
If you buy a PC from a manufacturer pre-installed and it doesn't work then it is their fault for not doing decent quality control, it is not the OS provider's fault that people cannot implement their product properly.
Vista does work, it has its problems (but so does any OS, especially one so new) but it does work... Linux also does work, and again has many problems... Problems are fixed with driver upgrades, software upgrades and expertise to do them properly, if you lack the fix then don't just blanket blame the OS provider for what is likely a 3rd party created problem.