But....
H.264 is just another video codec, and one that everyone will be able to view when Quicktime 7 is released. If Microsoft started advertising WMV10 as a major reason to upgrade to Longhorn, I don't think many people would take them seriously.
Windows users got upgraded to OpenGl 1.5 when the video card manufacturers updated their drivers, which was quite a while ago. Are Apple really offering a driver upgrade as a selling point? And while Apple certainly lead the way in getting the video card to produce fancy effects on the desktop, that's not new in this release.
I'm not entirely sure what that Core Audio does, but from reading the page, the only new feature is the ability to combine multiple soundcards into a single logical device. That's a nice trick, but how many people are actually going to use it? Also, Windows (and, I would presume, Mac OS 10.3) has no problem recording from multiple soundcards simultaneously -- it's just a bit more tricky to set up.
And as for performing better -- Apple have doubled the RAM requirements for Tiger compared to 10.3
Don't get me wrong, I like Macs, and I'd probably get one if I could afford it. But it always amazes me that every year, most Mac owners are willing to shell out a hundred quid for some updates that other OS's get free, and a few new applications.
If Apple released a "desktop applications pack" containing things like Spotlight, Dashboard, Automator, and released it for £25 or so, then that would be okay. But even the £60 student price seems like a rip off to me, for what you're getting.