Thanks for all the replies ....
Bought a neat combined aluminium heat sink with integrated extractor fan specially for 3.25" hard drives from Maplin .... bargain at £8 ...... very neat ..... (product code A97AJ).
The HD runs much, much cooler now ....... almost at room temperature ......
(Out of interest I looked at the Western Digital web site for my WD120 Gbye drive .... its spec had its max running temp of 60C .... that's extreemly hot to touch ..... but surley they must last longer running cool ??? must be worth spending £8 to hopefully prolong the life .... ).
Stay cool !