Cool Andy, I hope you make the switch one day!
If I may address some of your points:
* Mac OS X has improved dramatically in both functionality and features since 10.0.
* It has several system-level technologies that are leveraged by third-party applications, such as Address Book, Spotlight indexing (the data version of iTunes' smart playlists), Automator scripting (eg Photoshop workflows) and Dashboard (eg in Leopard you'll be able to make a dynamically updating widget from a "clipping" of any web page)
* Lots of other cool hidden features like screen zooming, printing to PDF from any app, and dictionary lookup in any app.
* What the Mac lacks in quantity of software it more than makes up for in quality. As well as being a minority, we Mac users are a discerning bunch, so only the best-of-breed software tends to survive. And most Mac developers model their apps on Apple's, which has gotta be a plus.
* Most of the major software titles (MS Office, Adobe, Quark etc) were on the Mac first, and the Mac versions are generally still better.
This Mac-aganda piece ends...