Do I need to upgrade?
Kaspersky AntiVirus 3.0 for WinGate is a major improvement to version 2.0.
Important: Kaspersky Labs has announced end-of-life for the scanning engine used by previous versions of Kaspersky AntiVirus for WinGate. What this means is that signature updates will not be available for previous versions after the end of life date, which is 31 January 2011.
Your existing Kaspersky AntiVirus 2.0 license will work in Kaspersky AntiVirus 3.0 (as long as it hasn't expired), so there should be no reason to stop you from upgrading.
If you are running 3.0.0, you should update to 3.0.1 to fix a signature update bug.