How many hands is a decent sample size?

[Metromancer]

I'm not sure if this is the correct forum to ask this question, but I'm rebuilding my confidence by playing at 0.01-0.02 NL on Stars and beating it for like 20BB/100. I would like to move up slowly and was wondering how many hands one should play to be fairly certain one can beat a given no-limit level, 20,000 or so? Thanks for any feedback.

[rubberloon]

Enough so your average win rate is greater than the standard error of your win rate.

[btmagnetw]

50,000.

[Idiotex]

If you even know what 20BB/100 means, you can move beyond 0.01-0.02 in my humble opinion.