If you have a bottleneck it should be pretty small. The 6100 being a 95watt chip runs cool and has a lot of headroom, have you thought about overclocking it? I've run my 6100 at 4.0ghz (xigmatek air cooler) since the day I got it and have loved it.
As far as what the last poster mentioned, there are issues with Crossfire that AMD has finally aknowledged. They are trying to address them with a driver update due sometime this summer.