I am going to reformat and reinstall Windows XP on a 5 year old Dell Dimension 8200.

I am not sure about something. There seems to be two different ways to do something.

After you push "D" to delete the partition and then "L" to confirm it, you are given a screen with the following three choices.

1. To set up Windows XP on the selected item, press Enter.

2. To create a partition in the unpartitioned space, Press C

3. To delete the selected partition, press D

Some people say that you press Enter immediately.
Other people say you press C and create a partition first and
then press Enter.

Does it matter which way it is done?

I think if you press Enter immediately, a partition still gets created, doesn't it?

Instructions that say to press Enter are here:
link
Instructions that say to press C are here (around steps 3 and 4):
here