Contact hotmail and tell them you want to cancell your accounts, tell them that the accounts have been hijacked and that you can no longer access them. If all goes well a hotmail technician will contact you and you can arrange to have the passwords changed. Worked for me a few months back when a trojan slipped through the defenses- they even posted messages on this forum. Thats the quickest way to get them to help you
Get a decent virus scanner and firewall- you can download free trials from most of the big name virus hunters now. Install the firewall and antivirus, use the firewall to kill all traffic and after the antivirus has been updated then run a scan. you can choose to allow only certain applications acess to the internet- start with just internet explorer and check the list of services running in Taskmanager by googleing for them- if anything is suspicious then kill it.
Don't take any ilegal actionagainst the IP addy you have found- it could be a proxy or dynamic IP in wich case it's you that will be up sh*t creek without a paddle. As mentioned above contact the ISP and provide them with all the details you have- a copy of the email sent to you showing the full headers will help.
If all else fails the it's time to wipe the box and start againjust remember to back up only the critical information. It's best if you compress all the files you back up, that way you can scan them for trojans/worms/virus's before you restore them.
And the most important thing are:
Don't open anything you get sent to you in an email before you scan it with AV
Block any suspicious net traffic
Get an Antivirus and prefferably an Internet security suite that contains a firewall.
Good luck!