FREE OF REGISTERATIONCOST, ANTISPYWARE

my computor is severly infected by spyware and viruses like TROJAN,i have downloaded some antispywares like system doctor, golden, drive cleaner, but after scanning they ask for registeration in order to remove or clean the infection.i cant register,it asks for money.tell about such an antispyware, which scan and removes free of cost or regiterartion.i have mc cafee installed but still attacked by spywares its strange. help me and soon