GuardXT- Site Security-Protection Against Hackers

Just learned that Joomla can have some security issues, can be hacked if you don't lock it down. Site's particularly vulnerable if you have PayPal on the site, 'cause that is what hackers are looking  for.

Nobody wants security holes. Just read about a tool you can install called GuardXT. GuardXT script will scan all the files independent of Joomla and helps check the security of your installation. Makes it easy to monitor files. What's more, Joomla Server Configuration Check gives you an overview of the more important security settings.

This is not a commercial for GuardXT. I don't know much about it yet.

Has anyone had experience with this tool? Would you share it?

Was told by my Host Agent that you need to be attentive to upgrades with Joomla, and failing to upgrade is the reason people get hacked.???? Any opinions on that?

Joomla's looking good, but no hackers please. What do you think?