How to convert ext2 -> ext3

[Reg Clemens]

How do I convert an ext2 file system to ext3?
I know Ive done this before, but cant remember the command,
and my searching hasnt turned up anything...

And while Im at it...
WHY is it that sometimes when you install FC4 you get
the option to build ext3 file systems and other times you DONT?

The current conversion is due to the latter fact.
I just put a new disk in a PII machine, and when I got to the
disk stuff, I could only make an ext2 file system.