BIDS is 2008 and SQL Server is 05

so i have designed SSIS packages that execute a stored procedure. the packages were designed in BIDS 08 and the stored procedures are sitting on a 05 box. i thought i could not execute SSIS packages designed in BIDS 2008 on a 2005 SQL Server Box.
NB i am executing the packages straight from BIDS. may someone please explain why i can execute the SSIS packages:S