I just learned from Marc Gravell that these are false:
Version.Parse("6.0") >= Version.Parse("6.0.0")

Version.Parse("6.0.0") >= Version.Parse("6.0.0.0")

And these are true:
Version.Parse("6.0.0") >= Version.Parse("6.0.0")

Version.Parse("6.0") < Version.Parse("6.0.0")

Version.Parse("6.0.0") < Version.Parse("6.0.0.0")

I'm gonna need more coffee.