I have had two WordPress blogs hacked into in the past. That was at a time when I was doing very little internet marketing, and until I found time to address the situation (months later), these sites were penalised in the search engines. They were not removed, but the rankings were reduced.
By default, the newest version of WordPress is pretty darn secure. Anything which may have been added to some fix wordpress malware fix plugins has been considered by the development team of WordPress . Before, WordPress did have holes but most of them are filled up.
Use strong passwords - Do what you can to use a strong password, alpha-numeric. Easy to remember passwords are easy to guess!
Keep your WordPress Setup to date - One of the easiest and most valuable tasks you can do yourself is to ensure that your other WordPress installation is updated. WordPress gives you a notice on your dashboard, so there is really no reason.
Install the WordPress Firewall Plugin. This plugin investigates web requests with heuristics to recognize and prevent obvious attacks.
Change admin username and your WordPress password, or at least your password, often and collect and utilize good WordPress safety tips to keep hackers out!