I think if you have a problem doing this installation for you system, take this task..
1. Uninstall that mysql..
2. Dellete the remaining file in your drive connected to that mysql...
3. Get Xammp installer... If you are familiar with this software, its is a apache friend which has a complete at stand alone software in 1 package. It has a Mysql, both old and new, php 4-5, firezilla for Ftp server, mysql Admin for mysql administration, apache 2.0,2.2 and soon.... :-D you can download it in
www.apachefriends.org/en/xampp.html. :-D enjoy it...