I don't know much about memory foam so can't really comment. A bed that sags in the middle will always give u a bad back however - so definately worth a look at getting a new one that will last and won't sag. in NZ we have a underlay called a magne sleep that people love here. works on magnetic therapy - no idea really how it works, but good for arthritic pain. so some of those things like magne-sleep and memory foam can be helpful... memory foam sounds interesting - it's something that you can really only trial and decide if it's right for you. sorry i can't help more there.