Debatable issue and imo not a necessary investment unless you want surge protection which I can just about understand. I think its just for tweakers and the analy obsessive ... others will disagree ...
Buy yourself a Tacima CS929 for £25 delivered and see what you think. If you don't find any difference then you have a well made surge protector for your kit. If you do then hopefully it'll be positive. If not, then stick it on the TV and DVD player...