Depends on where you work. This is anectodatal, but the office I worked at for 2 years, most of the people there knew enough about computers to know that having to switch back and forth was annoying and inconvenient. With most of our projects being on a time-table and with only a limited number of it people in the office, sorry but having the admin install everything ISN'T time effective and in turn, cost effective.
And KB, stop talking like an ms parrot. There ARE issues with vista and saying they don't exist or saying they're from the end user is jumping to conclusions.