|"Without third party software each drive can only have a maxiumum of four partitions."|
As in, four PRIMARY partitions. Up to three of the Primary partitions can be Extended partitions.
2000 and XP assign the drive letter it sees itself as installed on (the Windows partition - the partition \Windows itself is installed on) while running Setup, according to what other hard drive partitions Setup detects that have already been assigned drive letters.
When Setup detects no other such partitions, such as when you have a single drive and it has no data on it, it sees it's Windows partition as being assigned the C drive letter.
When Setup DOES detect other such partitions, it sees it's Windows partition as assigned the NEXT available drive letter (above C, any up to and inc. Z) AFTER the drive letters for hard drive partitions that have already been assigned, NOT C.
Which drive letter the Windows installation you booted sees itself as being assigned to is shown in System Information.
E.g. Windows Directory - C:\Windows, or D:\Windows, or whatever.
You can change the drive letter (above C) assigned to any drive, for a hard drive partition or optical drive, EXCEPT the one Windows sees itself as being installed on, in Disk Management, to any available drive letter, but sometimes you have to temporarily assign other drive letters in order to free up the drive letter already assigned that you want to use.
It doesn't matter whether Windows sees itself as being installed on other than C.
The only standard way of getting Windows to see itself as being assigned C (when it doesn't otherwise) is to run Setup from scratch, and to remove or HIDE any any other partitions present on the computer that Setup will detect as having been assigned a drive letter.
E.g. - if you have more than one hard drive, only connect one drive's data cable, or set all but one hard drive (the one you want Windows to be on) to NONE in the bios Setup (if it's IDE you may to change the jumper setting on the drive as well) .
- if the other partition(s) is(are) on the same drive, use something such as Partition Magic, or a freeware equivalent, to HIDE the partitionsyou don't want Setup to detect, before you run Setup.
The same applies if you are multi booting two or more 2000 or XP operatings systems on the same computer. If you prevent Setup from seeing the other partitions while running Setup, each Windows installtion will see itself as being assigned C - you can set up the dual or multiboot later - e.g. by using a command in the Recovery Console to make a new version of boot.ini.
You MAY be able to run a "Repair install" procedure, which does not delete the present data on the Windows partition - that MAY change the drive letter to C, if and only if you remove or hide other partitions before running it - however I have not tried that and I don't know if that will change the drive letter.