Research 2000 for WCAX-TV (2/14-16, likely voters, no trend lines):
Deb Markowitz (D): 43
Brian Dubie (R): 41
Undecided: 16
Doug Racine (D): 38
Brian Dubie (R): 43
Undecided: 19
Peter Shumlin (D): 35
Brian Dubie (R): 45
Undecided: 20
Matt Dunne (D): 36
Brian Dubie (R): 44
Undecided: 20
Susan Bartlett (D): 30
Brian Dubie (R): 48
Undecided: 22
(MoE: ±5%)
On the surface, those are pretty encouraging numbers for Republican Brian Dubie, but bear in mind that a disproportionate amount of undecided voters in every one of the above match-ups come from the Democratic column. Dubie, the current Lt. Governor, is the strongest nominee that the GOP could cough up here, but there's no doubt that he's riding high on superior name recognition right now.
And, in case you need a scorecard:
Deb Markowitz: SoS (1999-Present)
Doug Racine: Lt. Governor (1997-2003), '02 Gubernatorial nominee, state Senator (2007-Present)
Peter Shumlin: State Senator (1993-2003, 2007-Present), '02 Lt-Gov nominee
Matt Dunne: State Representative (1993-1999), state Senator (2003-2007), '06 Lt-Gov nominee
Susan Bartlett: State Senator (1993-Present)