OP (EDIT: and @LarryHunter) you're misunderstanding how Arturia apps are installed. Allow me to explain.
Firstly you don't need to uninstall VC7/VC8 before installing VC9. There is no 'chaos'.
1....New versions of VSTs in VC9 that are directly compatible with the old versions in VC7/VC8 will install over the top of the old ones, replacing them on your drive.
2....There are older versions of some VSTs within VC7/VC8 which have been updated and replaced in VC9 with new versions that are incompatible with the previous versions, for example Piano V3, CS80V4 and the separate Prophet 5 and Prophet VS VSTs. So Arturia leaves the old versions of these instruments installed for you, as well as the new ones, to prevent incompatibility issues with any existing projects that use them.
If Arturia deleted the old versions of the VSTs from your computer, you and other customers would then be complaining that (1) projects using the older VSTs don't work properly anymore, and (2) Arturia has illegitimately removed software from your computer which you legally purchased.
If you really want to get rid of your legacy installs and only see VC9 instruments, there are options in the Software Center to do so, which ideally you should have clicked before installing VC9. You could do it now (after installing VC9), but it might also uninstall some VC9 components (because they overlap) so I'd re-install VC9 directly afterwards using the Reinstall button, if you're going to choose that route.
But in reality you're making a mountain out of a molehill.