Some good points, but, just for your information in future:
Check to see if you have a file called Windows.old in the C:\Windows folder
Windows.old is located straight on the C:\ drive.
If you set-up a dual-boot system with both Windows 7 and Vista, then I'm not quite sure where your Vista files might be. Probably on C:\ drive if Vista was installed first - but that doesn't absolutely need to be the case. We'd need more information about what you did before being able to correctly answer your question if this is the case. Post back and tell us what you did if you have a dual-boot system.
Someone correct me if I am wrong with any of this
The system files are always on the C:\ drive. In a duel boot system, if you boot into Windows 7, then Windows 7 puts the partition with its system files onto the C:\ drive. If you boot into Vista, the same thing will happen. Now the Vista files are on the C:\ drive. So, the currently running Operating System (Windows only) will always have its file on the C:\ drive. Always. Arguably more accurate, the active partition on the currently used hard disk is marked as C:\. There is a slight difference between partitions marked to be made Active on boot, and partitions currently active.
Drive letters are relative to the Operating System running. Displays in Disk Management are not. This relates to the port the hard disk data cable is plugged into. This is not relative to the Operating System running.
Assuming that all hard disk re-connect properly, and don't need fiddling with (ie they appear in Computer, and not just Disk Management):
Partition on a disk are listed in order of which one has been marked as the Active Partition, the Active partition being assigned a letter first. The Disk Management view is to do with where on the hard disk drive the file are actually stored, in a round about way.
Let us assume that we have Vista installed from the factory, on HDD 1, in slot one, with the Recovery Partition on it. Let us assume that another hard disk has been added, Windows 7 installed, and then partitioned for Windows Data (ie not Ubuntu or anything like that)
We would normally see (not always)
C:\ Windows 7 partition
D:\ Windows Data Partition. It is on the same physical disk, but not the active partition
E:\ Vista partition. Is the Partition set to be the Active Partition
F:\ RECOVERY partition. Second hard disk (relative to Windows 7) and is the partition not marked as Active.
Anyway, I think some of that at least is correct. Feel free to correct, this is not my strongest area of computer. Good help Lorien!
Richard