Depending on the version of ZC you are upgrading from, the mods you have already installed may or may not work. I had to install the new admin levels mod because I took a site from 1.2.7 to 1.3.7.
I found the easiest way to do that upgrade was to install 1.3.7 in a separate location (I used another domain, but you can easily put it in a separate folder where your live cart is) with its own db. I tinkered with the look of the site in the test location. Once I was satisfied, I took the live site down for maintenance and uploaded 1.3.7 WITH the custom template to the live site. I changed the paths in the config files to point to the live site. When I ran zc_install, all I had to do was run the db upgrade since ZC 1.3.7 was already "installed". After that I took a look at what mods I needed to reinstall.
It worked like a charm. No data was lost and the site was back up in a few minutes.
The site in question is in my sig.



