XoloX always shares your /download directory and anyone else with XoloX can grab segments of files you are currently downloading. So if you have downloaded files, or are downloading files, then you are sharing. Some of your upload traffic may also be from sending XoloX updates out to members who got the program from download.com, as 1.12 isn't there yet if I remember corrently. (1.11 instead)

To see what you are uploading make sure to check "My uploads visible" in the tools menu and sit around staring at the downloads page... as any uploads that finish dissapear right away from the list, and no logs are kept as to what's been sent.