Famous™ said:
Cybergate, best free rat.
Actually not. Also depends of the version. The lastest free one is 2.3, and the server isn't really stealth at all, it shows a "install program" when the server is opened. The other popular version is 1.07.5, it is cool, but it will bug out and show a lot of dll errors if the slave has both Firefox and Chrome installed.
OP:
I've the lastest version of Darkcomet (5.3.1), if you want I'll send it to you in a zip.
Edit:
Darkcomet is the best free RAT.