Security breach

[abertini]

Hi, I have a site running the Genesis framework and the Enterprise theme. The site has been up for over a year and never had issues, till last week when someone or something hacked into it, the configuration of the site was messed up and I even lost access to the Admin console. Antiviruses also stopped IE from accessing the site because apparently it was trying to download some malicious software. After restoring the www folder from cpanel everything went back to normal. I then spent some time researching WP security, and I think I went through all the checklist to make sure it was secure. However 3 days ago the same thing happened again Using some tracking plugin I could determine that the files below have been modified, or at least visited during the attack.
Is there anything else you can suggest in order to make the site more secure and stop this from occurring again? It's a business website, and downtime means loss of revenue as well as waisted Adwords money

Thank you in advance for your assistance.

error_log
index.php
suspended.page/index.html
wp-admin/index.php
wp-admin/network/index.php
wp-admin/user/index.php
wp-content/index.php
wp-content/themes/index.php
wp-content/themes/genesis/index.php
wp-content/themes/classic/index.php
wp-content/themes/enterprise/index.php
wp-content/themes/genesis_old/index.php
wp-content/themes/twentyten/index.php
wp-content/themes/default/index.php
wp-content/plugins/index.php
moving.page/index.html