Because of recent events, I will update this.
as of 4/16/07:
Democrats
Strong Dem
Illinois
Massachusetts
Delaware
Rhode Island
West Virginia
Michigan
Arkansas
Iowa
Likely Dem
New Jersey
Montana
Lean Dem
South Dakota
Tossup
Lousiana
Republicans
Strong GOP
Idaho
Wyoming
Kansas
Alaska
Kentucky
Tennessee
Mississippi
Alabama
Georgia
South Carolina
Likely GOP
New Mexico
Nebraska
Oklahoma
Texas
Lean GOP
Virginia
North Carolina
Oregon
Maine
Minnesota
Tossup
New Hampshire
Lean Dem
Colorado
If you're gonna lean Oregon, Virginia, and Minnesota for the GOP then you HAVE to lean Colorado and New Hampshire the same way. John Warner's not running in VA and that seat is going to the Democrat. If Peter DeFazio runs in OR then Gordon Smith is toast.
On the other hand you have the incumbent Sununu who will show strongly and then a hippie running for the Dems in Colorado (not exactly a hippie state!).
I would lean VA and OR to the Dems. NH a toss-up. MN and CO lean Republican.