Virus threat

I have a cable modem connected to Time Machine, with the Time Machine being the router for my three mac computers. I allow my neighbor to access my wireless network, she is running a Dell PC. Does this represent a virus threat passing through the router to my apple machines? If so, what precautionary steps should be taken?

You can easily set up a "Guest" network and disallow communication to your main network. I have my router set up that way and when people come over, they get onto the Guest network and have access to the internet, but have no access to any other device connected to my main network.

Besides, Windows Viruses do not run on OSX.

Also, depending on where you are, allowing others to tap into your connection is technically against the terms of service of nearly every single provider on the planet. You may want to keep that on the DL.

And adding to what Deckyon has said, you are also eating into your monthly cap by alowing her to use your connection, presumably for free, and when you hit the cap you're going to get shut down, do it often enough (with Comcast) and they might require you to get into a more beefier plan to continue to have access..

By sharing your Internet connection with someone outside of your household you are actually acting as a mini ISP that's forbidden by most, if not all, ISP TOS..

Considering that they do their computing at work, I don't think they are looking for someone who checks their email a couple of times on the weekend. Thanks for the concern anyway.