Moved this to the general tablet talk section.
Welcome to AF Chadm01, Android 2.2 is call Froyo, most likely you will be unable to upgrade to ICS unless someone has made a custom version of the firmware for the type of tablet you are buying or if you are a developer and can make a version yourself.
If this is a inexpensive Chinese tablet I doubt there is custom firmware available. If there is or you are a developer then it would be free.
Depending on the specs there may be some newer games that will not run on the tablet. Do you have any info as to the model the tablet is?
Welcome to AF