Have you tried saving the library  as a template and including all content?

If that doesn't work, Bamboo has a desktop tool that may help (I've never
used it myself):

store.bamboosolutions.com/...mport-release-11.aspx

They have a 15-day free trial (though it's somewhat crippled) that might
work for you if you want to do it one time only...

You may also check this out.

stsadm.blogspot.com/.../...rtexportcopy-lists.html

This guy has 100+ free custom stsadm commands that are pretty nice.

Thanks a lot, the template method worked a treat!