The partition names are user specified at the time of formatting. If you just ignore the chance and skip to the next page, all your partitions will be unnamed except for the disk letter.
That's a recipe for disaster in a reinstall situation because disk letters are virtual not real.
They're just registry entries in the running system, and most likely will differ from one to another. The booted DVD is an OS in its own right and will assign letters to your unnamed partitions which are
not the same as the way you're used to thinking of them. That's how people "mysteriously" overwrite the system they were trying to keep despite being "sure I picked the right one".
If your partitions don't have descriptive labels already (
like this), you can easily provide them by right clicking them in explorer and using "rename".
That way when you're positioning your new install, you can be
absolutely sure it's going in the right place. (labels are physically attached to the partition in the partition table section of the MBR and retain their identity across multiple systems)
Your previous W7 install put its boot files on the XP partition (normal MS dual-boot design when adding a newer system to an older), so they will be unaffected by the new install, though you might find a couple of W7 entries after the reinstall. That can be tidied up with EasyBCD.
If the boot files had been on the W7 drive, that still wouldn't have been a problem, the install would just have created a new set, and EasyBCD would detect and autoconfigure XP for you afterwards.
