Marc, This is just a guess, but I think your 1.1 apps will work fine. The incompatibility issues, as I understand it, have to do with the IDE. You may need to install VS 2005 with the special Vista service pack in order to further develop your 1.1 apps. VS 2003 will likely have problems (though I havn't tried it). As for the experience, I've enjoyed developing in the Vista/VS 2005 combo. I'm using a dual boot with XP, though, so I can go back and forth. In XP, I have VS 2003 and VS 2005 running side by side.