But as long as you have it straight in your mind which is which, I wouldn't change things--unless you are obsessive enough that you will lay in bed thinking about it.
Thanks for confirming that these disk numbers do not matter. I didn't lose sleep over it and now I won't even have a second thought about them!
They could possibly matter in one instance. When Windows logs an event about a disk (bad sector, error detecting during paging operation, etc.) it will use the disk number to identify the disk in question.
So if the disk numbers can change each time you boot this could cause some problems identifying the disk mentioned in the event.
And yes, I have noticed the same phenomenon. First I had one disk only connected to SATA1. After installing Windows 7 it had disk number 0 as expected. Then I added two more disks to SATA2 and SATA3. And now I just noticed that these are getting disk numbers 0 and 1 respectively in Disk Management while my first disk (an SSD) have to be satisfied with getting disk number 2.
(Can mention that I changed the assigned drive letters of some card reader drives after installing Windows and before noticing this; I removed the drive letters for those and set them to mount in NTFS folders instead to save the drive letters for more important things. Could possibly have affected the disk numbering I guess)
Well, now I understand the advice to remove all but the target disk while installing Windows. You don't want to get the hidden boot partition set to another hard drive.