I am using SQL server 2005. I just tried executing your example given here. Though i don't commit the transaction 'a' i am getting the updated value '2' when i run select query. what could be the reason?

And also you are saying that the tempdb database is used for row level versioning stuff. But i could not see the 'test' table (which i created) in tempdb database. I am thinking that the 'test' table will be created in tempdb too. what do you say? Or else where does it stores versioning data?