Partition your drive as FEW TIMES AS POSSIBLE!
you will hit many problems if you try to partition this multiple times. your best bet would be to cut it in half, or thirds. Windows 7 is huge, and needs room to breath. Completely wipe your current Windows 7 install, and set partitions as above, then re-install to a blank partition at LEAST 30+GB. Although I personally can't work with less than 50GB on anything, especially if you want to upgrade to new builds later on.
as for getting another copy of Windows 7, you should be able to torrent it... I dont know if M$ still offers it free...