Here's my process so far:
Backed up my database and all the old wp files and folders
Deleted all the files that start with wp
Left the folders that start with wp intact
Uploaded all files from the zip of 1.5
Re-uploaded the wp-config.php file
Try to run the upgrade.php file but get this error:
"There doesn't seem to be a wp-config.php file. Double check that you updated wp-config-sample.php with the proper database connection information and renamed it to wp-config.php."