As mentioned, you can't go backwards. It's not the 32 v 64, it's the versions of the software. The compatibility level of the database doesn't matter.

The way you do this is

- script all schema and objects, run on the 2005 instance

- script all permissions, apply to 2005 server

- export all data, import into 2005 instance

You can do this yourself, but you might have FK issues, and it will take time. SQL Compare/Data Compare from Red Gate (I work for them), or any other set of compare tools, are likely worth the money if your time is valuable to get this done. However it's not a hard process, just complicated. It just has a lot of things to manage.