Vista laptops

I've had a series of laptops in for repair, all running Windows Vista, all about three years old and really slow and all failing with a variety of problems. What is going on?

They take ages to repair much more than I can reasonably charge the client for. Most have just 1Gb of memory and need all the accumulated programs removing from the start-up list before you can get any reasonable response from them. Running an anti-virus scan on them can take hours and I certainly can't do anything else at the same time. Windows Update won't run and I often need to manually load Service Packs. Even rebooting them takes ages. And all run very warm.

I suppose that they have all reached the end of their useful life, yet with our present economic climate people cannot afford to replace them.

I'm gradually working my way through the backlog.