re Windows 7 - I'd certainly wait until December before considering an upgrade because the software is only released for wide use from 22/10 (anyone running it now is using a pre-release version), and once tens of millions of people start upgrading, any problems will be quickly reported and not so quickly fixed.
As for 27 pounds, that's higher than some firms have been reported as charging (12 pounds springs to mind from a friend, but his machine doesn't have a DVD/CD drive, so wonder how the heck he'll upgrade!)
Re MS Office 2007 - I'm with BadgersPaw on it being bad that a school is not using an open source option - it's blinkered and pushes Microsoft into homes on top of too many businesses being stuck with using it...
Schools should be trying OpenOffice and opening the eyes of staff and students to there being 'other' solutions. When I worked in (higher) education in the 80s, there were some students bleating they could not work with Quattro Pro as they 'only knew how to use Lotus 1-2-3' - it's like saying "I cannot use this word processor because it's not Microsoft Word"...
True that needs learning time, to get the best out of any alternative, and indeed, there might be some feature that is missing, but the essentials are in every spreadsheet/ word processor/ database.
Parents ought to query any suggestion that particular software needs to be used (and if it is being suggested, then arrangements need to be in place to have the school get a general licence for it not to cost parents anything extra).
With the Microsoft 'master plan' of requiring large users to sign up to a 'new licence every three years' clause, I'm surprised they'd give it away free to anyone, even schools or charities.
If it is the case, then it might come up against anti-competitive regulation, though to be fair, Apple used to give at least a 50% 'discount' to higher education for systems (in the 80s at least) and Microsoft has reason to be worried about any large-scale switch to OpenOffice, given that is backed by a big name that's not entirely Microsoft-friendly!