I was reading up on this issue this morning. The following was part of Microsoft's warning.
From Microsoft:
To exploit this vulnerability, the attacker must be able to send a specially crafted request to port 135, port 139, port 445, or any other specifically configured RPC port on the remote computer. For intranet environments these ports are typically accessible, but for Internet-connected computers, these ports are typically blocked by a firewall. If these ports are not blocked, or in an intranet environment, the attacker does not have to have any additional privileges.
Best practice recommendations include blocking all TCP/IP ports that are not actually being used. By default, most firewalls, including the Windows Internet Connection Firewall (ICF), block those ports. For this reason, most computers that are attached to the Internet should have RPC over TCP or UDP blocked. RPC over UDP or TCP is not intended to be used in hostile environments, such as the Internet. More robust protocols, such as RPC over HTTP, are provided for hostile environments.
Based on the preceding statements, it appears that I wouldn't be at risk. (ports blocked, firewall, etc.) However, since I've been playing around with various VPN configurations, I installed the patch on my servers (2 of them) anyway - just to be safe - and I haven't noticed any adverse effects up to now. I'll do the W2K workstations over the weekend.