As long as your Interlink controller is for G3 or higher, then you're good to go[8D].
The G5 upgrade for 79 bucks, does not require any earlier disks, serial numbers, only that you own an Interlink controller from a prior version.
With RF, if you have an earlier version on your machine, the new disk will install the new version in a separate directory, it will not touch the earlier. The supplied disc is a full version.
Good luck,
Pete
http://www3.towerhobbies.com/cgi-bin...?&I=LXYET5&P=0