[JWait]

If it is a new install it would probably be easier to just re-install the skin. You will need your AUTH code, which is on the summary page in admin.

X-cart probably directed you to delete install.php (and some other things) when you completed your install, along with changing the permissions on config.php. You will need to revert them to what they should be for a new install. When you have done that simply point your browser to install.php, enter your AUTH code and choose a two-column format.
You will then need to change the permissions on config.php and the other things x-cart told you to do when you did your initial install.

A a side note, I don't delete the files, but change the permissions to 000. That way no one can see or access them. It appears to have the same effect as actually deleting them. While I can't say its perfect, it has worked for me.

When you are done you will probably need to clear you templates cache. Enter http;//www.yoursite.com/cleanup.php in your browser and if that doesn't work (sometimes it doesn't) login to admin and go to "summary" and click on "tools". Clear Templates is towards the bottom of the page.