It only affects XP's and possibly 2000's.
EDIT: Oh, and you can get it from being on the Internet, if you're not updated.
Here's a patch you need to fix your system:
http://www.microsoft.com/technet/tre...n/MS03-026.asp
And download disinfection info from:
http://www.f-secure.com/v-descs/msblast.shtml
Ice