Aornum is a task started with Windows which keeps in contact with its controlling servers, combined with an IE Browser Helper Object.
Ornum (its folder name in Program Files), iWon Plus.
Is included in more recent bundles of iWon software including the iWon toolbar and Prize Machine.
Yes. Opens pop-up adverts whilst browsing with IE.
Unknown. Aornum passes opaque strings of characters to its servers, the meaning of which is unclear.
Aornum downloads and executes code signed by iWon, for update purposes.
None known, though it will try to connect to iWon when you a file Explorer window, which is annoying if you have auto-connect.
Go to the Control Panel's Add/Remove Programs option and remove 'iWon Plus'. You will probably also want to remove the 'iWon EZ Setup' entry which is the installer (allowing iWon-signed code to be installed from a web page) and the 'iWon Search Assistant' which monitors terms entered into search engines and hijacks IE search settings.
(The 'iWon co-pilot' toolbar is not known to be harmful, you can choose to keep or remove it.)
Next, open the registry (Start->Run->regedit) and find the key HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run. Delete the 'Aornum' value. Now reboot and you should be able to delete the 'Ornum' folder in Program Files, and anything in the 'iWon' folder you didn't keep.