If you are having troubles with joomla 1.5, I reccmend using
http://vertrigo.sourceforge.net/
This is a little piece of software that allows you to build a loclhost type server on your laptop etc, so you can play with joomla without messing around with all the server settings, which can be difficult to find sometimes.
Secondly, because the "server" on your computer has not unwritable folders, you don't have to mess around with folder permissions
Finally, it gives you another server - when I have a problem with my on-line server, I sometimes switch to my local server to check on the problem, that way I eliminate any incorrect settings in my on-line setup
Also, if you go to http://www.itidiots.com/
They a couple of good videos on joomla 1 and 1.5
If you can't find the vidoes - install miro (usingmiro.com) and type itidiots to get HD video quality
enjoy
