Windows 7 homegroup and security questions

Question

I use my laptop (W7 HomePrem) for banking (and everything else) and I also frequently use free public wifi hotspots. Often I do both at the same time.

I strive to keep everything updated including Windows and other MS programs, Java, the Adobe players, QuickTime, etc, etc. I've turned off all sharing options under advanced sharing options. My built-in firewall is on, my AV is up to date and working. I don't do torrents or other high risk surfing, or open emails that seem suspicious or phishy. I always verify I'm logging into an https page and my Outlook is set to do all communication securely with servers. I use FF, keep it updated, and use some good phishing/security/etc type extensions for the help they can give.

Other than the possibility of connecting to a fake/imposter/phishing WiFi network, I feel I'm pretty safe and I haven't had any malware issues in years.

But now I need to share a folder so it is accessible to another computer on my home WiFi network.

-We are on the same HomeGroup.
-it is the only folder shared on my PC.
-I set the sharing permissions so that accessing it requires keying the credentials for a local "standard user" account that has a strong password.
-I really don't want to undo the sharing everyday before connecting to the free WiFi's and then redo it later to enable sharing again.

Considering my standard security precautions above, how do (a) HomeGroups and (b)me sharing the folder as I have, affect (1)each other and (2)my security when I'm on a free WiFi network? Thank you.

Edit to add info I should have included above:
-My pc is set to treat all networks as Public, except my home wifi which is classified as Home type.

Answer 1

Your thinking about it the wrong way.

You want to share files at home, but not when connected to public/open WIFI, right?

Read through "this"

Choosing a network location

The first time that you connect to a network, you must choose a network location. This automatically sets the appropriate firewall settings for the type of network that you connect to. If you connect to networks in different locations (for example, a network at your home, at a local coffee shop, or at work), choosing a network location can help ensure that your computer is always set to an appropriate security level.

There are three network locations: Home, Work, and Public place.

Home or Work

Choose one of these locations for home or small office networks when you know and trust the people and devices on the network. Network discovery, which allows you to see other computers and devices on a network and allows other network users to see your computer, is on by default. For more information, see What is network discovery?

Public place

Choose this location for networks in public places (such as coffee shops or airports). This location is designed to keep your computer from being visible to other computers around you and to help protect your computer from any malicious software from the Internet. Network discovery is turned off for this location. Note Note

If there’s only one computer on your network and you know you won’t need to share files or printers, the safest choice is “Public place.” To change a network location type

If your computer is part of a domain, you won't be able to change the network location type because it is controlled by your network administrator.

Log on to the network.

Open Network and Sharing Center by clicking the Start button Picture of the Start button, clicking Control Panel, clicking Network and Internet, and then clicking Network and Sharing Center.

Click Customize, and then click either Public (for "Public place" networks) or Private (for "Home" or "Work" networks). Administrator permission required If you are prompted for an administrator password or confirmation, type the password or provide confirmation.

Click Next, and then click Close.

Warning

Choosing "Private" permanently changes the firewall configuration to allow communication. This can be a security risk. For more information, see What are the risks of allowing programs through a firewall?