WordPress could not create directory or copy file

WordPress errors after setting up a new installation on the server can include these:

Downloading update from http://wordpress.org/wordpress-3.0.1.zip
Unpacking the update
Could not create directory.: /public_html
Installation Failed

Downloading update from http://wordpress.org/wordpress-3.0.1.zip
Unpacking the update
Verifying the unpacked files
Installing the latest version
Could not copy file.: /public_html/wp-admin/css/theme-editor.dev.css
Installation Failed

They are generally permission based errors and can be resolved by changing permissions (CHMOD) of the following folders to 777:

In wp-content there are 4 folders (plugins, themes, upgrade, uploads).
You can use a decent FTP program for this. I use and recommend the free WINSCP from here:

http://winscp.net/

It’s very stable and supports FTP, SFTP and SCP.