Sometimes, but not always. I've re-used OEM CDs on replacement hardware successfully, though at the moment I couldn't tell you exactly which boxes.
> It may be more expensive in the short run, but it pays off in the long because you keep reusing your software. A small business I worked for had over 20 different computer systems but we only needed 5 registered OEMs of Windows 2000 because I simply reused it.
Quite true.
Win2K was (IMO) the best OS Microsoft has ever produced, in terms of the balance between features and bloat/restrictions. I suspect I'll keep the 2K CDs around essentially forever. They just keep working.
XP has some fine additional features, but much of the time they're not worth the additional bloat and restrictions.
Vista (to return to the topic of the thread) is over the top so far it's unprintable. As a System Admin I have to support a number of Vista users along with our regular crew of XP users, Mac-heads, Linux fans, UNIX geeks, and assorted what-not. The Vista folks account for 80% of the problems, even though they're only 5% of the user base so far.
XP has some fine additional features, but much of the time they're not worth the additional bloat and restrictions.
I have a W2k machine side by side with an XP machine. I prefer XP, but I will keep my 2000 disks, along with the service pacs on CD.