The cool thing about Windows Server 2008 is the feature to be able to extend the system partition (make it bigger). So if you have a disk partitioned that includes the c: drive but you still have free disk space that has not yet been allocated, you can add that to the c: drive.
This is something you could not do before. Believe me as a server administrator, not being able to do this in the past was a huge deal. This was especially true in the bad old days of nothing but physical servers. If your system disk filled up, your only choice is to somehow replace it with a bigger one.
In the virtual world it became a bit easier since you could make the virtual disk larger, but you still could not extend it with diskpart as you could a non-system disk. You could still extend it with Gparted or linking to another OS as second disk and extending there.
Increase size of C in VMWare
Expanding virtual disk with VMWorkstation
Increase size of system disk part 1
Increase size of system disk part 2
But now whether physical or virtual, you can extend a system disk with diskpart on the fly with no downtime at all-very cool! Now of course you can do it with Windows 7.
1. To do so, just start a Command Prompt with Administrator rights.
2. Type Diskpart and hit Enter
3. Type list volumes
4. Select the c: drive volume --- like sel vol 3
5. I like to do list volumes again and make sure I selected the right one. Look for the one with the Astrix in front of it.
6. Type Extend
7. If successful, you will see message "Diskpart successfully extended the volume".
Go back and check the new size of your disk.