You know, I really find that whole Windows is crap argument silly.. After 34 years in IT, my opinion is that there is NO perfect OS.
I've supported, in an enterprise enviroment, just about every flavour of DOS/Windows, Unix workstations and servers, (including, god forbid ,SCO and HPUX), as well as Macs. The only OS'es that were reasonably reliable and secure were the various flavours of mainframe (MVS/VM/OS 370/390).
I run XP. My setup is relable and secure (Cisco Pix and a Radius server (why?, because I can), and it runs the applications I need to do the stuff I want to do, without crashing. If I want to play in the Unix/Mac spaces, I use VMware.
As far as PDA's/handhelds, I'd suggest that windows mobile is neither great, nor horrible. It needs a bit of work in terms of customization , to get it to a really useable state. One of my favorite setups was to use XCPUScalar to enable true speed control on the CPU, according to load.
Favorite OS for me ? OS/2 - favorite Unix? - AIX
My thought is you run what you need to run, to give you the functionality you want.

That's my .02... feel free to flame away, won't bother me...

Cheers
Harold