To boot to a DOS prompt you need WinPE - this you can get in the Windows Automated Installation Kit download.
Win 7 actually only creates two partitions from a standard manual install. Is your third partition an actual partition or just some left over unpartitioned space caused by the drive geometry? Both partitions are necessary for a successful boot, but unless you are imaging each machine separately (eg to a second drive or partition) then you are going to get activation issues as the operating system will recognise it is on different hardware to that on which the image was created and require re-activation.
If you need to reset the machine each day, would it not be simpler to have a virtual machine running on the PC which is just rolled back to a snapshot each day?
By the way, are these machines part of a domain? If so, how are you managing the automatic password change that the workstation account undergoes every 7 days which will make your image "expire" at the end of this time and need to be manually rejoined to the domain each time, unless you create a fresh image?
What you may not be aware of, is that the Ghost development team were all laid off long before Windows 7 was released so any kludges to add Win 7 support came out of a small team of maintenance engineers in Pune, as the next version of Ghost was never finished.
Paragon Partition Manager is cheap and works, and it bang up to date, as is Acronis Trueimage. Issues such as these should not be arising this close to the Olympics - this should all have been tested and put to bed weeks ago......!!