My hesitency with Vista is for the usual reasons, how slow it is, compatibility issues with 3 party apps, etc. I haven't heard too many complaints about stability. In the last week I've read alot about MS starting to move to Windows 7. Alot of folks out there, more knowledgeable then I, think that Vista will go the way of windows 2K. But who knows. I just have been real pleased with XP and don't want to change unless there is a positive reason to do so. For a laptop, I just feel better about sticking with XP. If I build a new desktop (which I probably will in the next 6 months) I'll probably give Vista a try in a dual boot setup. But I've heard that setting up an XP/Vista dual boot can be a circus.
Also, I spoke with HP, IBM and some other brands and no one has a laptop that comes with XP and Penryn together. The only two that do are Sony and Dell. I have a Dell now and I haven't been real pleased with it. I also gave up a Michael Dell when he led the way to outsourcing, firing thousands of US workers and giving their jobs to people in other countries. So much greed.
I would have gone with Asus, but they also don't have any laptops with XP.