External hard drive malware removal?

On Saturday, I was hit with a really bad virus on my main computer. I'm working on trying to solve that problem on another forum. (Here's the link to that, if it matters.)

Before the virus hit, I backed up my data on an external hard drive. How I can detect viruses on my external hard drive? I already ran Webroot's Spy Sweeper with AntiVirus on it, and it caught something called "JSInject-A", which it classified as a trojan. I'm currently scanning the external hard drive with Malwarebytes' Anti-Malware. Are there any other tools I can use to detect possible viruses on my external hard drive?

Thanks.