Adding custom profile fields to registration page moves "registration guidelines" text

When you add a custom profile field to the user registration page, using the core profile module, the "user registration guidelines" text moves to below the default "Account information" fieldset, instead of above it.

Steps to reproduce:

1. Install clean Drupal 6.4
2. Make sure you're logged in as admin
3. Enable profile module
4. Go to admin/user/settings and enter some text for "User registration guidelines"
5. Log out
6. Go to user/register; notice that the text you entered for "User registration guidelines" is above the user name field, as it should
7. Log in as admin
8. Go to admin/user/profile and add an arbitrary custom profile field; make sure to check the "Visible in user registration form." check box
9. Log out
10. Go to user/register; notice that the text you entered for "User registration guidelines" is now below the account information fieldset, instead of above it.

Please note that just enabling the profile module has no effect; only when you actually add a custom profile field, the bug manifests itself.

OS: Windows + Linux
Web server: Apache 2.2
PHP: 5.2.5
Drupal path: both tested it on http://localhost/drupal/ and http://localhost:8080/ (with clean URLs enabled)

Please feel free to ask for more details if you need to.