This want answer all your concerns, but check out the info from Animal in the link below.http://www.bleepingcomputer.com/forums/t/85348/addr2xinulcom/
Anyone can set up an account with MSN and Hotmail on any computer. You can have more than one account.
The pinging is probably him listing his blog with that site.
The only thing I see of concern is the networking change. Is your administrative account password protected? Do you have more than one computer or do you and your husband share the one? Does he have a guest account or just use your account? Describe your connection to the internet---dialup--cable--wireless
Edited by buddy215, 08 July 2007 - 11:56 AM.