Migrating data from mssql to postgresql

How can I migrate data from mssql to postgresql?

I have researched in the mailing list archives
and found some information. Some of them is related
to "migration wizard" tool, which is, I believe, a
plugin running on the pgadmin. But the current version
of pgadmin does not contain it (or I could not find it).
Is there any actual tool for this purpose ?

Thanks in advance.