I've found a solution to installing Catia on a Vista PC.......

........DON'T........you can't until Dassault come up with a patch.

Here's another solution ......

I'll base this on my problem. I brought a new HP laptop pre-installed with Vista Busines.

If you have brought a new PC with Vista Business installed you can down grade to XP Pro on the Microsoft downgrade option. You will need a copy of XP Pro which most people have brought seperately. I managed to get the discs from HP direct, I phoned up tech support and after a breif chat they turned round and said they would send me them free of charge. When you install them you use the Actuvate Using the phone option, you then give them your Vista Serial key and ask them to associate the Vista serial with XP.

bingo you can now install Catia