Ha! Found the info I was after - I really must improve my search techniques; with 20/20 hindsight this should not have been hard
I was searching within the MS Knowledgebase. Google did a much better job looking at it from outside
If you'r interested try Googling +ntfs+reserved+system+space It turns up many good results.
Here's what Microsoft has to say about it.
It seems I cannot reduce the size of the reserved space, but as I understand it, in the long run it will not impact on the capacity of the drive for data because of the way NTFS manages the reserved space and the competition from added files. So I guess I'm happy
Cheers all
AA