[eluser]obiron2[/eluser]
This is what I do/did for my second web site.
Install CI into htdocs
go into the config folder and rename config.php to config-base.php
Copy the application folder from the old site/dev system to the new site
copy the config file from the old site and put it in the new site config folder.
compare the config.php to config-base.php and edit any values that are site specific (e.g. site name, default controller etc.)
you may need to do the same with the database config file.
Test that the new site works in the same way as the old one then delete/remove/rename any helpers, controllers, models and views that you don't need.
If the original site was written correctly then there should be no values hard coded in these elements, anything that is required should be in the database or the config.
WARNING!! Your old sites are probably on 1.6.3 or even a flavour of 1.5 If you install 1.7.1 there may be things that don't work exactly the same.