Marking partition active w/recovery cons

I am attempting to repartition a disk (previously a dynamic NTFS data disk)using diskpart under the recovery console.

Although the disk has been partitioned and formatted the way I want it, I cannot see a way of marking a partition as active. I have installed Win2K but the disk is not being seen as being a valid system disk.

Other than reformatting as FAT and using legacy partitioning/formatting techniques I am not sure how to best proceed.

Any ideas?