I use it semi-regularly.  Various LiveCDs and "emergency" disks (specifically SysRecCD, as it a lot of useful tools including the always handy chntpw if you *ahem* forgot your local Windows password) mostly recently, although I do have a full install at home I play with from time-to-time.

My home PC has a wireless card, and I've found the only way to use it under Linux is to use the Windows driver via a wrapper (the name of this project escapes me at the moment).  Unfortunately recently I've been playing some games/simulators that only run on Windows, so not so useful there.

My distro of choice is Slackware, for 2 reasons:

- although it has nice GUI bits, it's always been a distro put together for sysadmins and those who either know what they're doing or want to get their hands dirty.  Therefore, you can always drop to a shell and do whatever you need to do.

- on a technical level, it uses "BSD-style init scripts", which is quite rare in a Linux distro.  Basically, the BSD flavours of Unix use one "master" startup script for each runlevel, whereas Linux and other "System V-like" unix variants use the System V-style init scripts, which is a whole lot of small scripts that get fired together for each runlevel.  To me, the BSD-style just makes more sense.  And, just so that Linux apps looking for it have something, Slackware has a compatibility layer of symlinks that mimic the System V approach if necessary, so nothing is really compromised by using Slackware.

At work we're a Windows shop, and I don't have a separate box to play with Linux and mine is too slow to run an emulator at full tilt properly, so I find myself using Cygwin fairly often.  It's a unix compatibility layer for Windows - it runs on top of Windows, but acts as a translation layer for most unix calls, so a lot of unix software can run on Windows with a straight re-compile in the Cygwin environment.

But even if you're not developing software, it gives you a BASH shell and all the normal unix tools, which is often handy, and you can see all your windows files, etc.