To the OP - are you looking for something only to protect against voltage spikes / power surges / brown outs etc, or are you after something that addresses line noise / RF? If the former, then as others have said a surge protector is almost certainly of value. If the latter, then you might be after a different beast (power conditioner). Some products will do both of course, and there seems to be a fair bit of knowledge here about those. I live in an old house, with old wiring - or not well-thought out circuits at any rate - and filters have been a godsend for me because they get rid of obvious background noise...