Beginning Jan 1, 2011 a Snell 2005 certification is needed for car or motorcycle For enclosed cockpit cars or streamliner motorcycles you will need a SA2005, for other bikes a M2005 seems OK.
The helmet must have a manufacture date not to exceed 5 years back.
Since that is the new rule, I would not even consider a Snell 2000 (even though is Ok thru end Of 2010) go ahead and get a Sell 2005.
When I raced bikes I wore Aria, Shoei, or Bell...
Maybe some of the go fast bike riders can tell you what brand and model helmet they wear ?
Charles