Horus and Ensemble are both available by ftp. Ensemble is freely available. To get Ensemble, go here and follow the pointers to the distribution.
The Horus binaries and sources are securely encrypted, and you'll need to get the decryption key. If you are a research user (either an educational institution, or a research lab), you can fill out a non-disclosure agreement, and send it to
Rosemary Odessa Department of Computer Science 4105B Upson Hall Cornell University Ithaca, NY 14853 Tel. (607) 255-9198 FAX. (607) 255-4428
If approved, she will send you the for the binary distribution (the source distribution is available to educational institutions only by special request).
If you are not a research user (e.g., a commercial company or an individual user), then you will have to negotiate an agreement with Stratus, Inc., who owns the commercial license to Horus. This may involve some money (but not necessarily). Please send e-mail to Robert Cooper (firstname.lastname@example.org) for information. Once you received the password, you can follow these instructions.