I think you should import "org.jboss.annotation.security.SecurityDomain" annotation (instead of "org.jboss.aspects.security.SecurityDomain").
ooops, yep your absolutely right !! things are alright now.
org.jboss.aspects.security.SecurityDomain was what eclipse put when i used ctrl+space for completion. I had to add a jar to the default classpath set by JBossIDE (deploy\ejb3.deployer\jboss-annotations-ejb3.jar)... good to know.
Thanks a lot for your help !!