Hiya Scott ---

In a word: SQL Server 7.0

Cost effective: SQL Server. Oracle has outrageous per-seat license fees.
Easiest to learn: SQL Server. Especially version 7.
Easiest to maintain: SQL Server. By far. Version 7 will even maintain it's own device sizes and partitions if you let it.
Easiest to migrate to: Even. Both require some thought.
Easiest to integrate: Is this a pure PC environment? If so, SQL Server. If not (there are some UNIX boxes or something) Oracle.
Scalable: Oracle has a slight edge.
Long Term: SQL Server. MS is really pushing it as "the" database engine for the enterprise and all the way down to the desktop. It is MS's long term database.