Well it's taken almost two months, but my DVD is not economical to repair. It's a DVD with built-in 5.1, so what I'm going to do is buy a stand-alone 5.1 system so that I can plug any 5.1-enabled device into. For example I can use it for my xbox, and rather than get a new DVD player I'll just play DVDs on the xbox too and when Blu-Ray players come down in price I'll get one. Then all that will remain is to replace my TV with an HD one and that'll complete the xbox experience and let me watch high-def movies too.
I've been doing some research and it seems there are cables etc I need to buy to plug the xbox into the system but I expected that.