Noone here is authorized to give you any type of legal advice. Phishy is just giving you his opinion on it. I wouldnt worry about it but there is always an off chance that something could happen...

It is just a risk for you to take. no open shares, disabling your guest account, setting an administrator password if you are in XP home (doesnt by default), using up to date patches and AV. A software firewall will help protect your PC but remember anything you do on the net *could* be sniffed and watched. That is why it is recommended to use a VPN, in your situation you dont have hispeed so you probably dont have it.