I'd agree with what Defunkt said, although a 2.1 set for £40, or a 5.1 set for £70 will be fine for games and when watching movies. Music is where these cheap speakers fail. Something like the Aego's will offer all round performance, albeit without surround sound, but there are some people who feel they are no longer worth £120. They are still very good, but the price has remained the same for ages AFAIK, and with Audio Engine's A2 monitor speakers on the scene for the same money, but with better sound quality, the Aego's once 5* rating has dropped a bit.
I think you have to think about what is most important to you. Do you want surround speakers for games and movies, but are willing to sacrifice sound quality when it comes to music. Are you wanting speakers that are able to reproduce music well, and are willing to sacrifice having surround for games and movies.
The fact you have a stereo for music, and assuming you can get it fixed, I'm guessing, having the PC speakers for music isn't so important. If you were replacing the stereo with PC speakers, then having some that reproduce music well would be more important.
The difference between a good stereo and cheaper 2.1/5.1 PC speakers, is huge when it comes to music.