SEF URLs with Joomla 1.5.15

What I Wanted

• easy legible urls

What I Used

• Joomla 1.5.15
• ISP using Apache 
• Putty (to ssh into my host) 

Step 1: SSH to Host (only necessary if your server runs Apache)
You will need to understand how to log into your server and minimal familiarity with linux. I used putty (www.putty.com).  So login, then..

1. Navigate to your joomla installation (eg cd path-to/yourdomain.com/)
2. Backup your htaccess.txt file (mv htaccess.txt htaccess.txt.bak)
3. Copy and rename that file (cp htaccess.txt.bak .htaccess) 

Step 2: Configure Joomla
Login as your administrator in the Joomla admin panel

1. Go to Site -> Global Configuration
2. Set both Search Engine Friendly URLs  and Use Apache mod_rewrite to 'yes' and hit apply.
3. Reload an inside page on your site, that might have done it. 

Step 3: If that didn't do it..
There's one more good trick.  Follow instructions at http://docs.joomla.org/SEF#Fixing_Broken_Site_When_SEF_is_Enabled.  This will also require you to ssh in to your host and alter one of the Joomla files.  If you're nervous about that back up the file first.

That worked for me.