You cant use web proxies for myspace, they wont let you post comments or bulletins or anything. You have to use ip proxies. http://hidemyass.com/free_proxy_lists.php
What I do is keep a jump drive with firefox on it, and have the ip proxy on it on the jump drive then all I have to do is plug in the jump drive any computer I go to at school and I can open up firefox from the jump drive and just go to myspace.com