input to formatted date

hi

i have three html dropdown boxes containg intergers which a user can
select as input for a desired date like:

11 03 01 

i want to display the input above as:

Sunday the 11th of march 2001

the one that causes the trouble is the weekday.
so my question is how can i extract/calculate the correct weekday
based on arbritary user-input in the format shown above?

thanks
allan