I bet you are amongst the majority of internet users who use one password for everything.
A password is only as strong as the weakest link and if you use the same password on multiple sites it is only as strong as the security on the weakest site.
And if you recently had an account at typo3.org you just found the weakest site as their site was compromised over the weekend.
Despite claims to the contrary Joomla 1.5 does have an ACL system. It may be rudimentary but when fully understood can be very useful.
To help you I've created a simple table with an overview of who can do what.
It should be obvious but it seems that people need a reminder.
You should only ever download files from their original source!! If you don't how will you ever be certain that what you are downloading is the real deal and doesnt have some hidden backdoor.
Not long ago a new version of wordpress was released at www.wordpresz.org which wasn't actually the real deal.
Don't fall into the same trap!.