I recently installed Debian on a small web server that took a while to set up properly (had to deal with a small learning curve). Since then, I've installed Linux Mint 6 and Ubuntu 9.04. I'm impressed with both, but Ubuntu 9.04 reminded me of Mac OS X - everything just works, works well, and is simple to use. I was blown away at how far it's come since I tried a beta several years back.
With that said, I'm a volunteer IT guy for a small non-profit (6 computers, 0 servers) Microsoft shop. The only reason we didn't migrate to Linux is that we have several documents, spreadsheets, and Publisher files that Linux simply does not have an adequate equivalent. OpenOffice is just not there yet, and Scribus neither is Scribus. Not to mention the pain in migrating the data from one platform to another.
I copied a Microsoft Word file to a test Linux 8.04 box, opened it in OpenOffice, and printed it to the local printer. The layout, font, and overall look and feel of the printed document was very different than the same file printed from Word. As far as I'm concerned, as long as Office suites aren't as robust as MS Office, users will continue to use Windows.