Instead of depending upon unreliable proxies, I suggest looking into Tor

http://tor.eff.org/

Tor provides a distributed network of servers ("onion routers"). Users bounce their communications (web requests, IM, IRC, SSH, etc.) around the routers. This makes it hard for recipients, observers, and even the onion routers themselves to track the source of the stream.

Basically what it is, is a network of tiny proxy servers that do not log any sort of connection data (unlike typical proxies). You would use one proxy that would connect to another proxy, and that proxy would connect to yet another proxy. All of them would be on the Tor network though, so you wouldn't have to worry about slowdown/disconnections or the like. In the end, this is how your connection to a website would look:

Your computer ---> tor proxy ----> tor proxy -----> tor proxy -----> a website

Now, after you install the Tor program and privoxy (just read the installation document http://tor.eff.org/cvs/tor/doc/tor-doc-win32.html ) the actual connection between proxy to proxy is automagic. No worries about trying to connect to multiple proxies as Tor will do all of that for you.

Give it a shot, as I highly recommend it more than ANY public/private/anonymous proxy. Higher speed ratios, and unlike normal proxies -none- of your information is logged or kept on the tor proxy server chain.

If you have any questions about tor, like how to get it to work with AIM/trillian/MSN, then don't hesitate to ask here, pm me, or contact me through AIM (see profile).