Formula to calulate number weeks and days between two dates

I need to know if there is a formula that can calculate the number of weeks and remaining days between two dates. Example: Start Date: 10/15/2009 End Date: 12/31/2009, I need the result to be 11 weeks, 1 day. I would appreciate any helpful input. Thanks!

If start date is A1 and end date B1 then

C1:
=INT((B1+1-A1)/7)&" Week(s), "&MOD(B1+1-A1,7)&" Day(s)"