How to find the Primary key of table

While creating some generic database related userinterfaces we always have find the primary key of the table in runtime. Previously in my Code generation wizards I used to search for the first field with "Id" as suffix and give the user chance to change. But now a senario came when i had create an update command of an sqldatasource in runtime. So i had get the primary key to for specifiying the where clause.

Now I could find the "sp_pKeys" in MS-SQlServer to get the primary key
Eg:

use pubs
sp_pKeys 'authors'