Another method is this:
Install Ubuntu to your desktop, then copy your home directory from your laptop, including the hidden configuration files (they are ones whose names start with a period, such as .opera) over to your home directory on your desktop. They will bring your individualized settings along with them. (Actually, you really only need the hidden files which you have not left at default, but it would likely be easier to grab all of them.)
If they include settings for software you have not installed to the desktop, the settings will be there waiting from when you do install that software. For example, I recently installed claws-mail to one of my laptops after about six months of using something else. It found the old ~/.claws-mail directory and mail store and was ready to go with all settings in tact.
If you have configured something in your /etc directory, such as your /etc/samba/smb.conf file or an rc.firewall script, you can grab them individually.