Spectral Dagger and Critical Hits[3.5]

[Beelzebub1111]

So the spectral dagger weapon [MiC page 59]...I have three questions:
1)Can you crit with it?
2)Do you crit on a 19-20 or on a 20 only?
3)What happens if you do crit with it?

[Galvin]

I think you can crit with it, because you can crit with the chill touch spell. I think it would only crit on 20, and on the event of a critical hit the damage is doubled.