I've been doing some preventative research and thought the following might help:

Although I'm reticent at installing plugins the following seem extremely helpful in combating being hacked and having malaware loaded onto your site:

1. WebsiteDefender WordPress Security (http://www.websitedefender.com/websitedefender-wordpress-security)
This plugin allows you to gain a free account with Websitedefender. The plugin scans your site and lets you know areas of weakness. It allows you to change the 'wp_' in your database tables to whatever you want.

The only caution with the plugin is that the website is still in beta. I'm assuming that once the beta is removed it will be a pay service.

2. Secure Wordpress (also by Websitedefender). This plugin runs scripts that that secure your site further.

3. Login Lockdown (http://www.bad-neighborhood.com/login-lockdown.html). Secures the login to your wordpress by only allowing a specified number of incorrect logins before locking out for a predeterminded time.

4. WordPress File Monitor Plus. Monitors you site for changes/adding/deleting of files and emails to let you know.

I'll update this as I learn more.