Hi,
which engines are available you will find at
http://technet.microsoft.com/en-us/forefront/serversecurity/dd940095.aspxSpamcure and other engines will be discontinued by december. So there are only Cloudmark for antispam and Authentium, Kaspersky, Microsoft, Norman and Virusbaster for Antimalware availabe.
I wouldn't enable all of the antimalware engines because that would cause too much load. I would enable the Cloudmark engine for antispam and only 3-4 from the antimalware engines and use different engines on the exchange so you have more security.
If you have any further questions please let me know.
Greetings
Christian
Christian Groebner MVP Forefront