How do you list all the primary keys of a table in SQL Server?

SELECT Col.Column_Name from
    INFORMATION_SCHEMA.TABLE_CONSTRAINTS Tab,
    INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE Col
WHERE
    Col.Constraint_Name = Tab.Constraint_Name
    AND Col.Table_Name = Tab.Table_Name
    AND Constraint_Type = 'PRIMARY KEY '
    AND Col.Table_Name = '<your table name>'

select *
from INFORMATION_SCHEMA.TABLE_CONSTRAINTS
where CONSTRAINT_TYPE = 'Primary Key' and Table_Name = 'whatever'

SELECT A.Name,Col.Column_Name from
    INFORMATION_SCHEMA.TABLE_CONSTRAINTS Tab,
    INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE Col ,
    (select NAME from dbo.sysobjects where xtype='u') AS A
WHERE
    Col.Constraint_Name = Tab.Constraint_Name
    AND Col.Table_Name = Tab.Table_Name
    AND Constraint_Type = 'PRIMARY KEY '
    AND Col.Table_Name = A.Name

SELECT TC.TABLE_NAME as [Table_name], TC.CONSTRAINT_NAME as [Primary_Key]
 FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS TC
 INNER JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE CCU
 ON TC.CONSTRAINT_NAME = CCU.CONSTRAINT_NAME
 WHERE TC.CONSTRAINT_TYPE = 'PRIMARY KEY' AND
 TC.TABLE_NAME IN
 (SELECT [NAME] AS [TABLE_NAME] FROM SYS.OBJECTS
 WHERE TYPE = 'U')