That's what bothers me, it just does not feel secure, and the "security" section of the Wikipedia page is discouraging. I love being able to just tell Windows to share a folder and imediately have these personal files on the Linux box (and with R/W access), but I don't want these files to be deletable or even accessible from the internet. I'm not even being asked a password! Can people all over the world access my shared folders without a password too?
The topography is: One machine Windows XP SP3, the other Linux Mint Debian edition, and both connected to the internet (and to each other) via a router that my ISP gave me. It has WPA-encrypted Wi-FI, but I connect these two via LAN cable.
Am I secure in my usage of Windows' file sharing (maybe by being behind a router)? Do I have to do something?