Let's look at the problems of having Macs on a Windows network. One year ago we bought 8 of the white MacBooks and 2 MacBook Pros. At first we used Boot Camp to run Windows XP, now we run it with Parallels but only because Boot Camp didn't support XP sp3 ( in june 2008) maybe they do now.
As a tech person for a school district I find them hard to do anything with. I image them using NetRestore to a firewire external hard drive. Creating an image takes over an hour and restoring an image is around 40 minutes. Compared to ghost this is unexceptable in my books.
Apple told me they would connect to a W2k3 server with no problems. Not! I had to turn on some macinstosh services first. You cannot easily map drives like you can on a pc. Creating an alias is as close as it comes. In my books the dock is a joke.
Even those accounts setup as an administrator do not have full rights to all folders without logging as a root user. That takes some work to "turn on" that feature.
Also, there is no "all users" folder to put shortcuts on. Apple told me that it would connect with a projector without doing anything special. Not! You have to turn on mirroring first.
I believe their iLife software to be difficut to use. I find burning a cd to be more difficult than on XP.
Apple brags up how their batteries last 4-6 hours but if you change the settings on a pc to match the apple defaults, it would do just as good in most cases.
the one advantage of a macbook running XP is it does run XP good and fast. Boot up time is much faster than a pc.
I think there is good quality software for a pc that will match the mac software. a lot of our students do not like the macs at all. The teacher is probably one of the few that do.
At the risk of sounding negative against macs, I am not 100% against them, only 90%.

I do think they have their place but I believe that will be short lived as their is continued improvements in Windows software.
Just my two cents worth,
Dave