How do I install software from a CD or DVD shared from a Windows 7 PC?
If you copy the CD to a disk image on the PC, you can put the image on a USB stick and transfer it to your Air. I am not sure how to do this on Window, but I'm sure you can find out how to do this somewhere.

WinImage looks like it should do what you want.

Also look at this article on creating CD images on Windows.