Use:
SELECT so.name AS table_name,
sc.name AS column_name,
sm.text AS default_value
FROM sys.sysobjects so
JOIN sys.syscolumns sc ON sc.id = so.id
LEFT JOIN sys.syscomments sm ON sm.id = sc.cdefault
WHERE so.xtype = 'U'
AND so.name = @yourtable
ORDER BY so.[name], sc.colid