Are you comparing at the same street pricing? Typically AMD is somewhat competitive at the same street pricing. Performance is also not directly comparable. For instance with graphics cards you can pick an ATI card and a somewhat equivalent NVIDIA card, and game A might get higher framerates on ATI while game B might get higher framerates on NVIDIA. With CPUs, AMD typically gives you more cores at a lower price, while Intel doesn't want anyone to have a quad core without paying around $200. Some software really excels with more cores, so in these cases AMD would be the better choice.
Additionally, until the Sandy Bridge processors showed up Intel didn't have anything good for integrated graphics, plus even the Sandy Bridge IGP doesn't support the "proper" framerate for Blu Ray playback. If you want to make a cheap HTPC, AMD is a very compelling choice on a
platform level, not just a CPU level.
My point is that it isn't a cut-dried "oh this benchmarks faster." After all, if all you cared about was the absolute "fastest" then you would buy an Intel Core i7 980X and call it a day. However, most of us don't have $1k to drop on a CPU, so we have to look at our budget and make the best choices at that price point for what we want our whole system to be. Sometimes it is an Intel CPU, and sometimes it is an AMD CPU.
EDIT: Damnit! My well thought out and well worded replies are
always late to the party.
