We deal with lots of schools in our local area and have been doing Windows 7 deployments since last summer. We have encountered few issues as most software developers we have spoken to have updated versions of products which we have obtained for free. This includes 64bit windows as 50% of our deployments have been at this level. If you speak to most software companies they are pretty good as they would rather give you a free/cheap upgrade than lose you completely (and various other schools as the deployments increase).