When upgrading the Web Community site from v4.7 to v5, these are the steps I took. These are notes I made from Lullabot's video Upgrading from Drupal 4.7.x to Drupal 5.x.

1. Login to Drupal as User ID #1 (the first user).
2. Place site into offline mode.
3. Disable custom and contributed modules.
4. Switch to a core theme (Blue Marine).
5. Upload Drupal v5.
• First, upload new Drupal files at root as yoursite.
• Rename old yoursite.com as yoursite-old.
• Rename new yoursite as yoursite.com.
6. Move over the old 'sites/settings.php' file and 'files' folder (and other files that might have edited). Chmod 'files' to 777.
7. Go to http://yoursite.com/update.php and run update script.
8. Install and enable upgraded versions of all contributed modules.
9. Upload and enable customized theme folders (not phptemplate/engine).
10. Go to http://yousite.com/update.php and re-run update script.
11. Transfer and test edits/hacks to modules and themes.
12. Test common tasks.
13. Create content.
14. Upload files.
15. Check for broken links.
16. If all looks good, move site to online mode.