Are Xanga Sites potential problems?

After spending last weekend working with Chaslang to rid my machine of spyware, I am really trying to figure out how to keep it that way. I have various spyware scans installed, my anti-virus is up-to-date, I have enabled the firewall in Norton (although I'm not 100% sure if I have it set correctly for protecting our 3-computer network.)

I am trying to help my kids (ages 14 and 17) understand what websites they should be avoiding. I've seen threads posted about issues with AIM...they often use that. But the biggy I'm concerned about their use of Xanga. Are we asking for problems when they maintain their own sites as well as visit others? Or am I just being worried for nothing?

Thanks for your thoughts.