Connie is worried that since her dad leaves his computer on, it's more vulnerable to attack. Leo says no, that's not how it works. There are things that Connie can do to protect him better, though:
1) Use a Mac (he does)
2) Get a router. The router will act as a dumb box that won't allow malware to pass in or sniff what he's going online.
3) Teach him to guard his behavior by not clicking on attachments or links in email, etc. And always be suspicious of them, double-checking the URL before clicking on the link.