Joomla 3 is the current version but they're still supporting some version of Joomla 2 (I'll leave that to you to check out). You also need to use VERY strong passwords (http://strongpasswordgenerator.com) to protect your admin directory.
I have a client who insisted on using Joomla (via another webmaster) so I secured Joomla-specialized hosting for him (apparently it uses more memory or CPU or ... whatever) and he got hacked (I'm sure he updated his Joomla installation). Apparently there was no malware installed but I recommended that he delete EVERYTHING and reinstall the latest version. After confirming that a maldet scan had detected no malware, I informed my client that, under normal circumstances, I would have terminated his account for failure to keep the CMS up to date because that is a major security concern to ALL accounts on the server.
No need for a wunderkind, all that's needed is a "script kiddie" who knows where to look for the latest exploits - your site could be dead in a mere matter of hours after release of an exploit.
All the more reason NOT to host at home! You cannot monitor 24/7/365¼ and, even if you could, you don't have the tools to monitor, block and repair the destriction wrought by any hacker, script kiddie or otherwise. Leave that to the professionals! I am so serious about this point that I won't even manage my own dedicated server - I leave that to the professional team at WebHostingBuzz!