>Yeah, but that complains when I have FK constraints set.

Take a look at this blog post

Delete all data in all tables in a database when you have foreign keys

From comment by Denis Gobo to this blog post:

-- disable referential integrity
EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL' 
GO 

EXEC sp_MSForEachTable 'TRUNCATE TABLE ?' 
GO 

-- enable referential integrity again 
EXEC sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL' 
GO