As opposed to a fake one?
Uncirculated $2 bills dated 1976 or later retail for about $3.
About $4
It is worth face value unless it is uncirculated.
A nice uncirculated one might retail for $3 but a dealer will only pay face value or maybe $2.25 if you're fortunate.
These are very common. They are only worth face value unless the are uncirculated.
Assuming it's from circulation, 50 cents. If it's uncirculated or proof, it might be worth up to $1.50.
As opposed to a fake one? That's unlikely because a $2 bill is too low a denomination to be worth counterfeiting. In any case, Series 2003 $2 bills are uncommon but not rare; an uncirculated one might retail for only $2.50 as of 07/2010.
20,000,000
It is worth face value unless it is uncirculated.
US $2 Federal Reserve Notes printed since 1976 are generally only worth face value in circulated condition. An uncirculated 2003 note might retail for all of $3.
If you got it in change it's worth face value only. It's not rare, so go ahead and spend it if you choose. It has extra value only in crisp uncirculated condition.
There weren't any series letters on 2003 $1 bills. You may be looking at the Federal Reserve District letter instead. In any case a 2003 $1 bill is too new to have any added value, even in uncirculated condition.
One Dollar