I posted aout Windows 7 a while ago, somewhere on this forum.
Despite the claims, there are no major changes between Vista and Windowns 7. It is mainly a roll-p of xisting patches plus a couple of newish applications/tools. You won't see any changes in that UAC system, unfortunately. But with some of the bug fixes, it will behave a little better than the current version of Vista. But certainly nothing major. It is probably less different to SP1 of Vista than SP1 was was to the original.
There is another SP coming soon for Vista. That will make the differences even less significant.
The purpose is really a smokescreen, so far as I can see. At the moment, businesses are ignoring Vista to a great extent. By issuing what is effectively SP3 but inder a different name, Microsoft are trying to enable themselves to say, "Look! No significant changes this time. Your people don't need to re-learn everything yet again." But they don't give people credit for brains, I think.
Many people in the business environment will probably miss this version as well.