1. 100 MB "reserved" partition for system files
2. C:\ Partition
You may have been told that you can then use Win7 Disk Manager to create additional partitions but it doesn't quite work. The MFT apparently sets itself up as usual on the middle of the C partition so you can't shrink your C:\partition by more than half. On a 1 TB drive that gives you a 480ish GB C:\ which most peeps who partition won't find acceptable.
One solution is the Easus Partition Manager which you can d/l for about $31. I used it on my son's box to reduce the size to 64 GB. WE did get a scare cause when windows rebooted it said itw as screwed up and had to repair itself. The repair went, or at least so far, seems to have gone OK. From that point on the Windows 7 disk manager works fine. Though it won't let you create an extended partition until you have used up all other primary partitions.