At least one major chain is taking advantage of the demise of its main competitor. Bed Bath and Beyond, helped by the demise last year of Linens 'n Things, turned in a pretty good second quarter, posting a 14% profit increase, a 3% revenue jump and a same-store sales slide of less than 1%.That's a lot better than Best Buy has done since its main rival, Circuit City, went under. Same-store sales during the electronics chain's second quarter fell 3.9% and earnings came in at $159 million, down from $202 million during the same year-ago period.So why is one doing so much better than the other? We're guessing that it has to do with what they sell. Could it simply be that less people are purchasing electronics than home furnishings? Or is it that Bed Bath has more of a price advantage over discount chains than Best Buy?