I'm a UK user and don't remember V7 being a UK version. IIRC it went Q5, Q98, Q99, Q2000, Q2002, QXG.
There are a couple of things to watch.
Quicken will not like two versions being installed at the same time. Some versions even go as far as automatically uninstalling earlier versions for you. I'm not saying it can't be done though.
Quicken will quite happily 'upgrade' your data file through many versions with no problems, but this is a one-way street! A backup is made - make sure you know where so you don't overwrite it by mistake. Even better make your own backup and physically remove it.
Quicken versions will not 'downgrade' your data to an earlier version. How can it - the data format didn't exist when the earlier version was written so it doesn't know how to deal with it?
Upgrading between different country versions of Quicken just doesn't work. Earlier US versions prior to V7 I think (please confirm or refute this US users) cannot handle multiple currencies, while the UK versions have always been able to and I believe the Canadian versions can handle US as well as Canadian $.
Hope this helps, but whatever you do keep a backup of your registration details, (Quicken is not supported in the UK any more so if you reinstall, it's unlikely to be able to reregister itself) and keep a known good backup of all your data files. Allowing Quicken to do this is perhaps best as you won't miss any then.