An update to the previous post: Safari for Windows.
I'd like to say that the Safari 3.01 beta update fixed the problems with my curved borders mentioned in the the previous post, but I probably ought to stick my hand up and admit that uploading the updated CSS file that's been sitting on my hard disk for about 2 months is almost certainly what fixed it! So Safari's new border radius properties do actually work on Windows, and they really do look gorgeous, all anti-aliased and shaded, against Firefox 2's pixellated efforts, or IE 7's non-existent effort :).
However still some quite quirky UI issues:
I'm really not sure I like the way that the Preferences window shrinks and grows every time you change tabs, and the fact that it's all instant apply with no 'OK' or 'Cancel'.
Also the Mac-style window re-sizing is really beginning to wind me up, particularly as the cursor doesn't change to the 'double-headed' resize arrow until after you start dragging in the one place that actually works, so there's absolutely no clue which parts of the UI you can or can't grab to resize until after you click the mouse to try it!
And finally just noticed that clicking the File menu on a non-resized window (with my Classic XP style) gives a really ugly blocky overlap of the window edge.