how to better secure my comp

don't reply to email it's most likely those pricks that sent spyware and are gonna try and con you into paying a fine that's fakes as well
they get the money and con you into another fake fine by fooling you by saying
"we got info from your isp info"

best thing to do is call your isp and see if they actually know anything about the email and it's authenticity

may i ask were you downloaded file from?
not that limewire crap i hope or those other pissy music download apps
live wire uses java script with is 100% not safe it's a hackers paradise