The becta report does say that upgrading to vista would cost each school about 24,000. We have perpetual licence for our school and that costs me £25 per seat. That entitles me to the latest OS & office so the cost will be hardware and deployment.

We will be going vista probably during the summer.

good choice, 350 million to upgrade... 

i would go with edubuntu for all the education needs. It's free and has everything you will need (including openoffice with full odf support preinstalled)

runs on old or new hardware just as good

a good number of goverments are already doing it

While I was away from work (a local primary school ICT tech), someone did a rush order of a new computer without consulting me. 

I was greeted by a Vista machine sporting Office 2007 on my return. Apparently "change" is a better sales pitch, far more important than consistency (the rest of the school is XP Pro with Office 2003).

Unfortunately, this computer is now the Head-teachers (since he had none at all before). I await the complaints about why he can only read his files on that computer, not other machines.

As much as schools might be "advised", few will take notice until that advise is handed out to more than a handful of people who might understand. (Another special-needs school along the road was "planning" to convert to Vista even when it was still in beta).