On the subject of Parallels, it comes with a feature to skin the windows apps to look more like OS X which is powered by MyColors. You do have to turn this feature on in Parallels before it is downloaded and enabled though and I would always recommend anyone with Parallels does this.
However we do not sell any products which work on OS X itself. I did see that there are some apps to skin OS X at least for older versions so they may have been updated for Lion.
Actually, you can apply the 'Mac OSX look' option in parallels at any time, it's an option in the menu, even after you've installed it (I used it when I evaluated parallels, it was cool 
).
I've searched for customization options for OSX, but nothing current seems to be available (some icon changing programs seem to be the limit of what's out there). I think snowman is right, Apple apparently freaked out when their users decided to 'think different'
Uvah,
There's no particular reason for your friend to return / replace the macbook itself, it can run windows just fine (either as a stand alone install or with boot camp), unless he's managed to snag an old powerpc version
I've got my macbook pro running windows using boot camp, just because I do want to mess around with OSX from time to time (just for the heck of it), but I boot to Windows something like 90% of the time.
Depending on which macbook your friend has, pretty much the only weirdness is the trackpad, and really only in the difference between tap to click and press to click. Otherwise, it works quite nicely with windows. I'd use boot camp just for the ease of getting the proper hardware drivers, but windows works perfectly well on my current mac laptop.
