My RC1 install of Windows 7...is on a 50GB partition, currently has 13GB free. I don't have a lot installed on it.
The size of the partition for the O/S...should depend, in part, on what else you intend to put on that partition. I put the O/S, updates, and programs installed on my boot partition. There's no reason for me to put anything else on it, I have several hard drives and multiple partitions on those drives.
I would suggest decreasing the size of the Win 7 partition to no more than 50GB.
If you cannot adjust the partition size using Win 7 tools...which, it appears that you cannot...you might try the software at http://www.partition-tool.com/resource/res...n-windows-7.htm
I have a copy of Easeus Partition Master (download the Home Edition) installed and it will allow you to reduce the size of your C: down to a manageable level. 1TB is too much for any partition used for anything other than pure storage. FWIW: My 1TB drive is comprised ot two partitions used solely for storage.
Other software will also allow partitions to be easily resized...this merely happens to be the one free one that I have ever tried.