I attended a PC Magazine sponsored event called "Everything Longhorn" a few weeks ago.
The general consensus was that it was very Mac-like, and from the beta demo they're right. The "Aero" interface has a lot of transparency, drop shadows, and zooming and fading, which are not new to OSX users. They've also added something called "Safe Sleep" and "Quick Resume" which, again, are not new to Mac users.
IE7 will have tabbed browsing and RSS support. Outlook Express will have built-in spam filtering. "Search" is everywhere. Users with Admin rights will still have to authenticate before doing true Admin-type tasks. Stop me if any of these sound familiar.
It was difficult to say how well applications would run on it, as they were simply showing what was built into the OS at this point.
The minimum requirements for hardware running Longhorn/Vista is 512 MB of RAM and a video card with 32 bits/pixel and 64 MB of graphics RAM. The hardware must carry a "certified for Windows XP" label (or, more accurately, meet the requirements to carry such a sticker).
Like johnny said above, Microsoft keeps dropping features from the OS. I heard on the TWIT podcast a few weeks ago that WINFS is not currently on the schedule to be included in Vista at all. (Of course, they also repeated the rumor that there are to be seven different versions of Vista available, depending on the features you want.)
Moral of the story-- if you want to wait and your HP can handle it, get Vista. My recommendation: all these features are in OSX right now, so go for a Mac.