I run XP ... and when I plug my Kobo in, it does show up in Windows Explorer ... and appears to be like another drive ... but I don't think it functions as "another drive" ... so just simply close out of the popup. Don't try to "explore" the file structure of it ... because I don't think XP will let you.
Now ... with ADE, I found that I had to start ADE first and then plug my Kobo in ... and then ADE recognizes it.
The other problem you'll have is if you try to "eject" the Kobo via "my computer". Windows XP just won't do that ... so you have to go down into the "safely remove hardware" icon on the task bar.
I don't know about the Kobo desktop software ...
Hope this helps.