it's designed for anonymous browsing in exactly the situation you describe. i've used it very successfully from behind corporate firewalls. biggest problem is that its' popularity has increased greater than the bandwidth available so there are times when it can be pretty slow (think: when america is awake) but i have found is often ok in the morning. must admit i haven't been using it recently as have good and unrestricted access and (not currently!) trying to hide anything.
how about trying tor, breglis?
http://tor.eff.org
it's designed for anonymous browsing in exactly the situation you describe. i've used it very successfully from behind corporate firewalls. biggest problem is that its' popularity has increased greater than the bandwidth available so there are times when it can be pretty slow (think: when america is awake) but i have found is often ok in the morning. must admit i haven't been using it recently as have good and unrestricted access and (not currently!) trying to hide anything.
good luck.