As a small database on small system
Do you mean simple PC? I run MS Access with 3GB database, and it survived. MS Access is "free": bundled in MS Office pro, you have MS Office anyway, right? You can access Access database (MS Jet Engine) via ODBC and DBI just fine. Your SQL will be multi-platform as long as you will use only standard SQL and avoid any proprietary extensions - but DBI will wisely guide you to use standard SQL only ;)
To make errors is human. But to make million errors per second, you need a computer.