Web Cache Appliances

Just trying to see how widely used web cache appliances (like the line offered by 3COM) are used over actual proxy server solutions in a 100+ employee company with heavy Internet users.

I read up on the web appliances and I’m still fogging on howmuch benefits they actually offer over a traditional proxy server.

Any insight on this? What do *YOU* use for speeding up your Internet access times/web caching?