It is important to note that many add-on products will require updated versions in order to work with different versions of ACT!. If you are using any specific add-on(s), you should check with the add-on vendors to see if they support the new version and the procedures to get an updated build, if required.
For ACT! 2010 some add-ons (like Handheld Contact) just require a new download while others may charge an upgrade fee for the new version.
When upgrading ACT!, it is usually a good idea to uninstall any add-ons first. Then perform the ACT! upgrade and then install the latest versions of the add-ons after checking they support the new version.
This also applies if you want to upgrade your MS-Office version or your operating system – you should confirm that your version of ACT! supports this or if you need an upgrade.
Checking these things first reduces potential disappointment if you later find out you need other upgrades that might not yet be available or that you hadn’t budgeted for.