60mb from a single website seems a lot. An average webpage will be kb or only a couple of mb. Someone else mentioned adverts, all those flashy graphics and things are probably done in flash or silverlight and obviously carry a lot more overhead than just html. A brokers page will probably have a lot of these but 60mb still sounds a lot.
You do need to monitor it yourself though. Is it only certain pages that download more than a couple of mb? What is on those pages (any sound, movies, large images, animated adverts etc)? Beyond that there are 2 posibilities. The web page could be booby trapped, scripted to download software to your PC which is not likely to be good software or, if the heavy usage is whenever you are connected to the internet it is something on your PC. This something could be Windows update, legitimate applications you have installed may also call home to update or it will be virus/malware or some sort. You can download tools to monitor what applications use the net and where downloaded bytes are from and going to.
