We recently got two new laptops for one of our salesmen and one of our managers, and they came with Vista (kind of an experiment on my part, I figured I could always go back to XP if it didn’t work out).
And so far, I’m pleasantly surprised, and both users are happy.   More details below for anyone who wants to see the longer version.
Vista does seem to be somewhat of a hardware hog. But these were new units, and I ordered them with more than the minimum processor and memory, so the performance is actually pretty good, better than the machines they replaced running the same programs.
And since they were new boxes pre-loaded with Vista, I didn’t have to worry about drivers for existing hardware, so I can’t speak to that issue.
I loaded our standard compliment of programs for the Sales staff: MS Office 2003, Adobe Photoshop 7, a couple of simple programs written in house, nothing special.  In both cases, I used the built in facility to transfer files and settings from an older XP box, and in both cases it worked with no problem.
On one laptop, I had to set it up to print to a networked printer (HP LaserJet 4100 with a Jet Direct card).  With the XP machines I’ve put on the network, I’ve often had small problems getting XP to see the printers.  Nothing serious, I’d have to enter the IP address by hand, or add the port manually.  On the Vista box, I started the add printer function, told it there was a printer on the network, it showed me a list of the six different HPs, let me pick the right one, then installed the driver.  No problems, went perfectly the first time.
With the other unit, the printer was an old HP Inkjet with only a parallel interface, which the laptop didn’t have.  I got a $13 USB to parallel adapter, plugged it into the printer, then into the laptop, and Vista loaded the USB adapter, then saw the printer and loaded that.  It did take two tries, however.  The first try didn’t install completely, I had to unplug it, remove the device, then plug it back in.  Then it installed both devices with no problem.
Although I did the warnings as I installed programs, configured the network, etc., I didn’t think it was all that bad.  Users may well get conditioned to always allow changes, I guess time will tell on that.
So far, both users report no problems (with Vista, there were a couple of reports of things that I didn’t get transferred correctly, but I believe that was my error).  One user says Vista is ok compared to XP, the other seems to think it’s definitely better than XP.  He was able to make it work with his home network connection (wireless connect to a new DSL installation) with no problem, and it still connected the office network correctly.
So although I was very leery going in, as I said above so far I’m pleasantly surprised and cautiously optimistic.