I think I'll go with that, after a few minor alterations.
SELECT Nodes.Caption
, DateTime
,PortCount as 'Port Count'
,ActivePortCount as 'Active Port Count'
,(PortCount - ActivePortCount) as 'Inactive Port Count'
FROM UDT_PortUsage_Detail
join Nodes on Nodes.NodeID = UDT_PortUsage_Detail.NodeID
where DateTime between '12-03-2013 13:30:00' AND '12-03-2013 14:30:00'
I'm only going to run this report manually, so putting in the dates by hand won't be too bad versus having 24 lines per node to wade through.