As a short term solution I had to purchase 2 used disks off TradeMe. This should keep the server going a bit longer until I can find a way of getting a new server.

The current 36G drive, apart from being full, was badly fragmented. After moving some temporary, IIS log and SPSearc index files over to the new disk, I had enough free space to start a defragmentation.

The defrag is still running and I still have to move the content DB's to the new disk. It seems like the server is already more responsive.