I own a pizza shop and I want to accept bitcoins but I'm still majorly concerned about how to keep my coins secure on windows.
Set up an account on mybitcoin.com and pick a very strong password. Use the online wallet just as you would a local wallet.
Frequently change your btc to usd at one of the exchanges so you're not exposed to too much currency risk. The minor risk of losing some bitcoin will be equivalent to having your local cash registers robbed. The upside is the love of all the local BTC users.
(I am in no way affiliated with mybitcoin.com, but their site is pretty slick. I like it.)
mybitcoin.com is the last place I would look for security. They did nothing about the MtGox security breach, so users lost over 4k BTC from the site.