At what point should I have my Windows developers upgrade to the latest release of Windows?

Question

At what point should I begin upgrading our developer's machines to a later Windows release?

From experience, Microsoft typically has an epic fail about every other O.S. (I am really not trying to start a debate about this, it is my perception let it be) i.e. 2000 was a stable and useful O.S, yet m.e. didn't do well, xp was a great O.S. that many businesses still use, Vista didn't do well (I know that the reason this one didn't do well wasn't really Microsoft's fault and that Vista and 7 are the same major revision), while 7 seems to be an excellent O.S. that will be around for a while--sort of like xp is now.

Anyways, this makes me reluctant to upgrade our development machines to Windows 8.

• a. I don't want to cost our business a ton of money for an O.S. that will only be used for a year or two.

• b. They also have to have linux dual boots, and I have read that Windows 8 and grub will not play well together.

I do want our developers to develop in the latest environment and to have a leading edge in any technology they are developing with. I do want to stay ahead of--or at least with--the technology curve, yet I want it to make business sense.

So in particular, should I upgrade their machines at this point? In general, what calculus should I use for deciding this sort of thing?

edit

They do write desktop UI applications as well as ASP.NET applications. Also, I do make sure that they always have the latest release of Visual Studio.