Yeah " Stupid windows" has had me pulling my hair out since 95it often gets assigned a drive letter when external media is plugged in or hotswaps are plugged in, just a bug in windows I guess. Everytime I plug one of my hotswaps in drive I appears on my computer too, without the hotswap though it doesnt have a drive letter assigned. Not sure why, but from reading around quite alot of people experioence the same with usb drives and hotswaps. Stupid windows is what I pout it down to lol.
Partition doesnt have to be on the same drive, infact I think the way windows 7 works (although im not sure) is that the boot sector doesnt even have to be on the same physical drive at all as the OS itself. Not entirely sure on this though, but my system at work has the boot sector on essentially c: along with linux, however the OS itself is installed on my secondary hard drive. Not reall sure why they do ti this way.