Open vs closed primarys

You must have read about unhappiness in Delaware by now. The Party's senatorial candidate, Mike Castle, got beat by the Tea Party candidate, Christine O'Donnell. Party people, Karl Rove, the loser himself, and other pundits have been wailing and gnashing their teeth claiming O'Donnell is unelectable and the dastardly Tea Party has thrown to Delaware Senate seat to the democrats.
I moved out of Delaware 40 years ago and haven't been back much since. So I have no clue as the the electability of anyone down there any more. But, if O'Donnell can win the primary she must be doing something right. The nay sayers respond that only Republicans can vote in the Delaware primary and O'Donnell is too something or other and the independents won't vote for her.
Up here in NH we have an open primary. Independents can vote in the primaries and we allow voters to switch party allegiance on election day and then switch it back on the way out the door of the polls.
Independents are important. They hold the balance of power. Most places have 40% registered democrats, 40% registered republicans and the rest independents. Who ever the independents go for, wins the election. With an open primary, the independents get a say in how conservative or how liberal the party candidates are. As a rule, independents are more middle of the road than party members. So allowing independents to vote in the primary has the effect of nominating more electable candidates.
With an open primary, NH republicans have nominated a field of good solid conservatives, people with name recognition amount the voters and honorable records of public service.