I'm sorta amazed that this thread hasn't become a religious war...

You can use both innodb and MyIsam for very large datasets. In fact, a lot of the most popular web sites use MySQL. The best thing is to contact MySQL and talk with someone very familiar with what you are trying to do and then see how it compares.

There are third party backup solutions for MySQL. There's also mysqldump which is nice to dump a small database (schema and data). Sorta like Oracle's datapump but text based.

I'm sure MySQL could point you in the right directory for query tuning, but one nice feature was the slow running query log. You could activate it and MySQL would write any query that ran long to a text log file. You could then begin optimizing with the queries causing the most trouble. Quite helpful if you ask me.

Others have mentioned PostgreSQL. Postgres is another nice database. To me, Postgres tends to track Oracle and MySQL is more like a MSSQL (yes I know there are missing features), but it's always dangerous to make those comparisons :^).