[Staren]

As long as your on a safe site it doesn't matter. If you're on high speed internet without a router or firewall, anything that's going to get in without you doing something is going to get in if the browser is open or not. Windows firewall blocks the vast majoraty of that stuff. Remember most viruses requre you to do something, go to a website, open an e-mail attachment. The only thing I'd worry about is of there is someone physicaly around the machine you don't want to sit down and read what you where doing.