Is there any information about diffrence between scyld,sce,rocks and OSCAR?

[Zou Guangxian]

hi 

   i am a newbie and plan to build a cluster .but which package should i choose?Scyld ,sce, rocks  or OSCAR?what about the diffrences between them? 
   i have learn a little about scyld ,but it is a commercial tool.:-(
   Regards
               weck.