Resize partition option greyed out

I have a HP Proliant ML310 G5 server running Small Business Server 2003. My server has 2*250GB SATA hard drives, one of which is not in use. The drive I am using has been partition into two; a 40GB system partition (C:\) and a 210GB data partition (D:\). I need to resize partitions as I am low on disk space on my system partition (less than 4GB) and I have installed Partition Manager 11 Server Edition. If I try to use the Express Resiz Partition wizard I receive a message stating no adjacent partitions and if I select one of the two partitions and click on the Partitions menu virtually everything is greyed out (see attached screenshot). Can anybody explain why I am unable to resize partitions and what I can do to fix this?

Thanks

David

 

What does it say in the help files about resizing dynamic disks?