Finally my 440GB of images on the Tank drive has a backup. The prospect of losing them had haunted me after the PC crash. They are stored at a second location on a 1TB drive inside the new PC. I am amazed at the speed of a full spec (i7 and 8GB Ram) 64 bit machine. It opens CS5 in 2 secs and a 250MB image in less than 1 sec. I know all this seems superficial, especially in the context of what I was doing in a wet darkroom but the power and speed of the PC will enhance my work. In the past I had not used Layers to their full extent, mainly due to the time it would take processing a 4 layer 1GB file. Consequently I worked live on the image and regretted it due to the lack of correction available during the final stages of PP.
The only drawback I can see at the moment is CS5. Yet more learning and hunting for familiar controls, perhaps I should buy a book.