Link: The New York Times > Technology > Circuits > You There, at the Computer: Pay Attention. [Free Reg. Req.]
I am big on getting into flow and I have alerts turned off and if I am trying to get something done I often turn off all the other applications I usually have open so I can concentrate.
I try to get about 2 hours of flow time in, in the morning. I hardly ever get all that time in flow but it try. Then I use the afternoon for all the short tasks of email and the like.
Distractions are okay, they are good at changing the mindset that may be holding you back, but interruptions while doing something important are frustrating.