'A lot' weaker is highly debatable. In benchmarks you can see the lead, but in the real world I'd be hard-pressed to tell the difference. There may be one or two games where the difference is bigger, others where the 7770 has no lead at all. I definitely wouldn't call the differences 'a lot' though - the 7770 is hardly in a whole new league. They're very comparable. I'd far prefer to go with the better manufacturer when there's so little performance difference to talk about.