On backups...
Back up your database(s) regularly. Look up the docs for your host control
panel, go into your MySQL admin and export your Db to your hard disk.
Keep local copies of the themes you use, plugins, any customizations, and
and static pages that you might have.
If you have a cpanel host you'll have an option to backup your entire site,
stats, logs, themes, databases, everything. This is
especially handy
if your host shuts down your site for too much traffic. Just move to your new
host, upload the backup, reset your domain nameservers, and you're
good. The shutdown happened to me, twice, with different sites.
You might also want to look at something like
http://Mozy.com for backing
up your local data.
Maybe someone will find this useful.
Greg