I'd say yes and no. My company has began making preparations for the switch to Vista. They plan to have it done by April (supposedly when MS support for XP is finished).
Seems to me that there are two reasons why people/businesses are switching to Vista.
1. They have to for one reason or another (eg many vendors no longer selling XP, lack of compatibility with new devices or the fear thereof)
2. They like it? Despite all of the drawbacks, if you can afford a Gig or two of RAM and a dual core processor, then Vista can look pretty good. It just looks cool.
So do I think the Vista SP1 RTM will increase sales of the OS?
I don't think we'll ever know. Sales of Vista will most likely increase no matter what, just because MS says so.
A+, Security+, HDI Support Center Analyst, MCTS: Vista