I currently have a single HDD with the following partitions: C = NTFS primary #1 (XP) D = FAT16 logical for DOS stuff E = FAT32 logical for data files & documents F = NTFS logical for installed applications If I add a second (slave) HDD formatted with something unrecognized by XP (such as Linux ext2 or similar), will XP still assign letter "D" to the unknown format partition thereby screwing up my entire installation? Or will it skip letter assignment since it doesn't know what it is, leaving everything else working? The existing drive is pretty much full, so I prefer adding a second drive, since I've got a couple of spares available. Thanks.

Windows will skip any partitions it doesn't recognise and not allocate a drive letter. Windows 98 does it all the time when it comes across an NTFS drive. If you were to put an primary NTFS/FAT32 folder on this new drive that would alter the drive letter assignment. However, with Windows XP that is not a problem as you can reassign drive letter to anything to all drives except the boot/system drive. Stuart

But is you do run into a problem with a drive letter, XP lets you change them around in the Disk Manager. All but the drive with XP on it. Do yourself a favor BACKUP!