By the way, you can check if CHMOD's are good, here:
Joomla 3.2 back-end: System --> System Information --> Directory Permissions (tab)
Another advice for you, you can set FTP - here: Global Configuration --> Server Settings
it will help you to install extensions in most cases without changing CHMODs.
p.s.
Remember that 666 for files and 777 for folders is not safe setting!