Stopping RAS for 95 and 98 computers.

Current Scenario: RAS dial-up via a Cisco 3500 IOS 12.3 pointing to an IAS 2000 server for RADIUS using PPP with MS-CHAP v2 only.

Problem: We would like to block all Windows 95 and 98 computers from being able to login to the RAS server. We need away to do this without a client agent.