Damian, my information in post #6 is correct - the DVD Player (a Toshiba SD220E) is one machine, the VCR a completely different machine (a Daewoo combo model- which also has an inbuilt DVD recorder that I don't use). This VCR has only recently been included in the setup as I was given a large number of VHS cassettes which I needed to view.
The reason why I have looked at using the old computer, was that from earlier posts,it looked like I may need to store the decrypted Humax files locally near the projector and this was one way I thought I could achieve that.
I agree that something like the Raspberry Pi may be a better solution, as it is much newer and so I am now looking at the recently launched Raspberry Pi 2 model B and also another contender the OSMC Vero that recently launched and has Gigerbit ethernet(see getvero.tv). My only problem is that no HDMI works on either the Denon AVR or the Panasonic Projector, so some sort of conversion will need to be identified in order to connect locally in the utility room.
I also now have bootHDR mode installed on the Humax, so I will shortly be trying to transfer decrypted HD recordings through the network onto both the old computer as well as to the Computer Server, in order to see which workflow is best.