If you're looking for a Proxy Client (a program that changes/updates proxys for you) I'd reccommend Stealther 2.7
I've actually gotten the chance to review it myself and I was quite impressed...
It has 3 modes:
Normal (no proxy)
Super Stealth (proxy loaded into a proxy etc)
Although they want people to pay for it, so you may have to take a break to find a crack on www.astalavista.box.sk
and only grab the 22 or 27k download since its the only one listed that actually REGISTERS the program for you.