I tested the 6Core Opteron CPU's on a Dual setup and unfortunately even though these were supposed to be the best AMD had to offer on a server/workstation platform they were pretty poor performing against the Overclocked i7/Dual Xeon setup never mind against the Intel 6Core Xeon..
its going to be 100% dependant on what you run, some stuff AMD is already very competitive, some its not, price wise though is what we're talking about. A 6 core AMD at 3Ghz will beat a 4core i7 in many things. The 6core i7(well i9 probably) will be faster but it will cost probably £700 and up here, the 6 core AMD will most likely come in under £250, possibly under £200 which should see if comftably ahead of most of Intel's range in performance, probably the best price/performance ratio of any chip you can really buy(except a 550 that unlocks to quad core or something).
The majority of the server market doesn't give a monkeys about pure performance, its about what they can get for a price point, if they can by more slower setups for an overall more speed for the same price, they will.
AMD's server stuff, in several area's is insanely good value for the performance they offer, and theres many area's the 6 cores beat Intel's quad cores while being cheaper.
Its very unlikely that any home users(typical home users, gaming being the most intensive thing they do, the odd unrar, encode aside where performance isn't critical) will need a 6 core in the next year anyway.
Said it time and time again, for the majority of home users pretty much any quad you can get in your system is more than enough for now, by the time games "might" move on to require more power we'll be strictly in Bulldozer and Intel's next architecture territory, which will bring around a lot more value, new mobo's most likely and so I really don't think many people will see any value out of small upgrades over the next year.
A 6 core sounds great at £200, but if you've got a quad, you'll be hard pushed to see the difference, 3dmark, a few benchies, smeg all else.
The best thing I guess is for those that don't have quads, 6 core cpu's in at the top end in AMD's sub £200 price bracket should push the better quads prices down even further. Intel won't be seeing that with a single model at the uber high end part of the market. A £700 6 core isn't going to push down your £150 quad core at all. A £180 6 core for AMD should push its top to bottom quads down in price though.
