Shoutbox

no, you don't.
You can change the drive letters for your drives using the Computer Management MMC (Start > Run > compmgmt.msc). Select the Disk Management option on the left. Right-click on the partition that you want to change, and select "Change drive letters and paths"

HOWEVER, since this is your system drive, I don't think you can change it. The only cause of this problem, as far as I can think of, is that when you re-installed, you didn't write over the old partition. To solve this, when in Disk Management, there is only one partition. If the data isn't important (if you were trying to format once, it probably isn't) right-click on the partitions and delete the extra ones. Get a DOS boot disk, and then use fdisk to delete the remaining one. you can then re-install windows on the drive, and you should the be able to make a partition over the full disk, instead of just part of it.