I'd suggest using something like Monolingual to remove the other languages
http://www.macupdate.com/info.php/id/7758

At one point there was a similar app to remove printer drivers, but I cannot seem to find it.

You can migrate VM virtual machines, no problem there at all. That is probably the easiest way to get XP onto the MBA. However, that will take either VMware Workstation (cost) or Server (free) on the Thinkpad and VMware Fusion (cost) on the mac.

Another option that would work for either VMware Fusion or Parallels is to make an "image" of the XP CD and copy it over to the MBA, then use it as a virtual CD-ROM for the install. Making an .iso (image) from CD should be trivial on Windows, but since I've been MS free for over a year, I'd be hardpressed to name any programs (nero does come to mind).

Once you have an .iso of the XP disk, simply copy it over. Then in either VMWare Fusion or Parallels, edit the settings of the virtual machine such that the CD-ROM drive uses the image file, not the physical drive (it will be very apparet in the settings). Then you can install XP like normal.

Frankly, if you have VMware Workstation or Server for your Thinkpad, your plan is probably easier.