3
If you use comments
Make sure you activate the modules in the same order they were activated on your original site, otherwise comments to those modules will not reffer to the correct modules.
This may not seem to be that big an issue on the face of it, but if your original site had any modules removed etc the numbering as looked at in admin will not simply be 1,2,3,4,5,6,7,8,9 etc it could be 1,2,5,6,8,9,11,12,13 or something like that
Take a hard copy of your modules table and xoopscomments tables as it is on your original site and have a look at the mid and name columns in modules
When you upgrade and have the original modules (or maybe latest versions) working if you have some unlinked data like comments this will help you set the com_modid id's in the xoopscomments table
Then you can use the sql update command to alter the com_modid values to reflect the new module mid value.
No doubt now someone will point to a module that does this for us