You can spend quite a bit less and still have one fast rig. Honestly, that motherboard is overkill - I can't imagine spending nearly $400 on a motherboard unless it offers something I absolutely need that a $200-$275 motherboard doesn't have (like when nVidia first offered SLI). I'd rather have 8GB RAM and a $200 mobo..
Also, with Nehalem coming out later this year, I'd rather take the new chip architecture over a process shrink in Intel's tick-tock CPU releases when spending big bucks. Current reviews of Nehalem show that it has a substantial enough increase in performance to make it worth it. For a process shrink CPU in the tick-tock releases, I'd get the cheapest availalbe and OC the sucker.. like the E8400.