pgAdmin II questions

I just finished upgrading from FreeBSD 4.6 to 4.8RC and I'm trying to do some things with pgAdmin II which are giving
meproblems. 

I remember creating a db called taxcal and it's listed there. However, I don't remember creating a db called pgsql.

Is this a db that the postgresql needs or was it created by mistake, maybe as a result of an erroneous create command?

Also, I can't drop it (by right clicking on it and selecting drop object from the shortcut menu. After being warned
thatthe action cannot be undone I agree and an error comes up: 

"An error as occured in pgAdmin II:basActions.drop:

Number: -2147467259
Description: ERROR: DROP DATABASE: database "pgsql" is being accessed by other users

Another thing I need help with is the appearance of both "template0" as well as "template1". I can't seem to delete
template0because the error from the drop action informs me that it is marked as a template.