You've made a number of fundamental "faux-pas" here.

Firstly, you've used Fantastico to install. Not the way to do it, I'm afraid...

You infer that you trashed the original files as they were "full of viruses". If this is the case, then all customizations in the original store are gone.

Did you do any backup of the "old" files at all? Did you preserve your product images? Do you have a backup of these anywhere?

You did keep the database, it seems. Are you pointing the new (Fantastico) install to the ORIGINAL database?

Looks like you are...

... and what is happening is that your old site was probably version 1.3.7 (or earlier) and Fantastico has installed 1.3.8 ... and you are now pointing 1.3.8 FILES to a 1.3.7 DATABASE.

The message is saying this to you, and requiring that you do a database UPGRADE.

There are help and tutorial items on upgrading properly.