I've used various OS's since DOS 2.1, and honestly most of the so called tech talk about superiority of one OS to another is really a matter of preference, and truthfully one of familiarity.
Ever since Windows NT came out, there really haven't been many major improvements on the true technical side of the Windows OS. Pre-emptive multitasking was basically it, the last major technical 'innards' advance in Microsoft desktop operating systems. The rest of the changes have been 'gimmicks' or 'planned obsolenence' - ie not supporting the OS with future drivers and packages like DirectX.
There was a ton of hype when XP came out, just like now with Vista. Personally, I think Windows 2000 was the best OS that MS made. XP added a bunch of unnecessary glitter on top of Win2k and dumbed down the interface in an attempt to make it idiot proof, but there was really no substance to it. Win2k was the last MS OS I ever bought, although I work with and have to support XP machines at work (and on my work laptop, an IBM T31).
The main thing I like about Tiger, and OS X in general, is its unix side. The shell, the ability to download and compile standard C/C++ programs and have them install in a very 'standard' way is OS X's real strength. It makes OS X a convergence point between a commercial OS with a clean, standard interface and the open source software movement. Basically, if you have OS X you don't really need Linux, and you certainly don't need Windows. You have the capabilities of both already (with the exception of kernel hacking OS X). Right out of the box Tiger has gcc, perl, make, python, shell scripting ability, java, and a programming IDE. Yeah you can *make* windows do all that, but even then compiling any program written for unix will require at a minimum changing path names in the make files - and probably a good bit more since MS doesn't like to use standard libraries or headers.
There is the BIG BIG difference between OS X and Windows (all of them) that goes right to their core, and one most people don't grasp.
MS makes single user multitasking operating systems. OS X is a true multi user multitasking operating system. There are ways to 'emulate' multi user characteristics on MS operating systems, but at its heart MS windows was never meant to be a multiuser system. I am not talking about being a file server here, I mean multi user in the sense of having multiple people logged into and running programs on your box. With windows, you generally serve up files which are run remotely. That isn't really necessary with OS X.
A good example of this is windows terminal vs telnet to OS X. Open up a windows terminal session and start running a job, then try to figure out who's id that job is running under. Guess what? You can't. Open up a telnet session to your mac and log in as a different user than what you have logged into the GUI as. Type 'who' in a shell session and you can see who is logged in. Any processes they start will show up with their user ID.
What I'm saying here is that in windows, the OS is built around the GUI.
In OS X the GUI is built around the OS.
It's a big structural difference that isn't going to go away.