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I strongly advise you to upgrade to the latest version in the 2.0.* branch (2.0.13) for security issues, but upgrading to 2.2 is not necessary unless you want to make use of the new functionalities. Upgrading is easy, go to the download XOOPS page and look up the upgrades. A readme is provided to help you performing the upgrade.
I am the BEST.......... at overstating things! -