I have Proxy 2.0 on W2K AS with SP1. I want to upgrade to ISA server. I have a VPN running on the Proxy box and an Exchange server (5.5) behind the Proxy. When I upgrade what filters and allows am I going to have to define? Will I have to upgrade all the clients as well since we have the WSP client on the machines?
What gets kept, and what gets whacked, depends on what mode the ISA Server is installed in, and the group membership of the user installing the ISA Server. Check out the upgrade guide on the ISA Server CD to get the details. It *does* make a big difference, so you have to know what the specifics are before performing the upgrade.
The Winsock Proxy client will work with ISA Server. I haven't seen, and haven't heard of any problems with using it.
You don't need to make the Exchange Server a Winsock (Firewall) client, as it will work if it is configured as a SecureNAT client. It should still work as a Firewall Client, though, if you have made some special configuration changes in the wspcfg.ini file. However, I would suggest removing the Winsock Proxy client software from the Exchange Server can configure it as a SNAT client first, and see if that works.