I'd heartily recommend building a small P100/64 Meg ram linux/bsd box to run either mySQL (lightweight, fast) or PostgreSQL (full featured, moderate performance).
the odbc connector in postgresql is one of the better ones out there. We get nearly the same performance from pgsql via the odbc connector as we do with native connection. and it's much faster and more stable than interbase, which suffers from a very poor odbc driver (the stock one, I understand there's a very good commercial one.)
Lastly, I think there's a version of mysql for windows, I'd start with that first, it's much more stable and much faster than interbase.
