How I do it is

I Bob Smith on June 1, 2011 hereby give my two week notice whereas June 14 will be my last day of work for Widget Company. Short and sweet.

If they ask why I just say a new opportunity came along and I am taking it and leave it at that.
I don???t tell them that the guy next to me refuses to believe he has ADD and ask me a stupid question every couple of minutes and reminds me of a dog humping my leg or the senior people make rules for everyone to follow except them.
Management should know the problems and not relay on me.

Also for the most part I do not have anything personal in my cube. I have pictures but they are print outs from the color printer. Where I am now they wait for you to leave the building and call you at home and tell you that your presence is no longer required.