Sandy,
Here is the link http://www.microsoft.com/sql/migration.
there's also the equivalent guide for migrating from SqlServer to Oracle, the "Migration Workbench"
http://www.oracle.com/technology/tech/migration/workbench/index.html
especially the paper at the bottom "Migrating a Microsoft SQL Server Application to Oracle White Paper" makes a quite complete comparison and mapping between "equivalent" Oracle and SqlServer features.
Me, too, I'd suggest to check Oracle XE first thing.
HTH Alberto -- Alberto Dell'Era "Per aspera ad astra" -- //www.freelists.org/webpage/oracle-l