Removing a trojan

[Eric's collar]

My sister clicked on a span email supposedly from facebook which was quite believable as it was from a .facebook.com address. It had an attachment that was a .exe and I'm poetry sure it was a trojan. My fears were confirmed when I ran a scan on windows security essentials.

What steps should I do next? It's already changed the desktop background. What programmes should I get.

My sister is worrying that her bank details will be stolen and all her fb passwords and hotmail. Does she have reason to worry?

 

[Eric's collar]

I removed the trojan using microsoft security essentials but it reappeared on a second scan. Running malwarebytes and it had 3 objects detected but they were from a keygen. Any way to really make sure it's deleted?

 

[Eric's collar]

Restated and security essentials detected it again