You may want to look at VNC. If I'm not mistaken, it was jointly developed by AT&T with Olivetti Labs. It is freeware, open source, and works well over TCP/IP. The things I don't like about it vs PCA are:

1) Only one password to gain access to the box, no ability to set up multiple Id/password combinations or talk to the NT security system. Not a huge deal if you logout of the host server before ending your connection.
2) No built in file transfer applet.

Things I like about it:
1) Only one password to gain access to the box <g>
2) Slightly better performance in my opinion

HTH.