Hardware/Software Question

A Freind of mines computer has a virus on it but she doesnt have internet so she cant get antivirus i was wondering if i put her harddrive in mine as a Secondary Slave could i run my antivirus on her harddrive and clean it up also the virus is a trojan horse she doesnt remeber the name also if something went wrong whould it affect my computer or her harddrive more i was already planning to do all this in safe mode if that helps