MyISAM versus InnoDB tables

From DreamHost

"A general guideline could be as follows: if you require multi-statement transactions, advanced isolation levels and row-level locking, foreign key constraints, or otherwise have a requirement for ACID features, go for InnoDB. Otherwise, simply use MyISAM, the default.

If you have a message board application with lots of selects, inserts as well as updates, InnoDB is probably the generally appropriate choice for the actual message board tables."

MySQL Storage Engine Architecture: Details and Comparison

Remember that you can chose a different storage engine for each table so think about the type of information stored and how users will interact with it when choosing a table type.