Upgrade Vs new install??

After a big scare with a virus, and hoping I have resolved it, I was going to update my Zencart, but with ver 1.38a, it is a huge job.

Is it easy to just install the new version, tweak it over time, add all the products and categories? then when ready, transfer the old (still working) store to the new one? (and then deleting the old)

I may have an advantage here, I have a North American store which is fairly fresh, with only 20 products, and an Australian version which has been going for 10 months. My theory, close the American one, latest install on that, copy pasting products from the Aust. store, then same for Aussie store. and bob's my uncle.

Guy

One thing I really would like to know, is it easy to do this, and then transfer the database to the new store to retain customer details, e-mails, previous sales etc? (same as the Australian store when I get to that one)

Zen Cart provides an automated process to upgrade your store database. You won't lose anything in your database if you upgrade the database using the formal upgrade instructions.
The upgrade of PHP files etc is up to you though. Instructions are provided for the recommended approach.