I was just checking out the weekly newsletter on DistroWatch. One of the articles dealt with cloning a new computer like your old one. Down in the comments section on reader talked about a feature in the Ubuntu software manager app.
From what I understand once you have the OS installed on the new computer you can then open the software center and under the "File" drop down menu you will see an option to sycn to another computer. Click on that and a list of installed app's from the old computer will be listed on the new. You can then go through the list and select which ones you want then then let it do it's thing. Move your personal files over and bingo your new system should be set up. Sure saves a lot of searching and installing.