here's how i did it:

installing windows 7 along with 100mb partition - sysprep and shutdown
capturing only the c: drive (installation) into a .wim file.

deploying onto a clean disk as following:

creating a 100mb partition as c: (ntfs, active, label="system reserved")
creating a second partition and assigning letter d: (ntfs, label="windows").
applying the captured .wim onto drive d:
using "bcdboot.exe d:\windows" so the bios can find the installation.
windows boots up and once i'm on the desktop the partition with windows is now c: and the former 100mb c: drive is my system reserved partition with no drive letter.