2 hours? Most odd. I'm on a 4MB connection, and it took me less than that, less than an hour on recent install actually. Suggest you open Synaptic, choose Settings from top menu, then Repositories, then look thru the list and find one that seems more "local" to you. My ISP is one of the mirrors, so I use them, and works very quickly for me. 
Like I said,
run Repository Speed Test, and you'll get the fastest repo available for you
then 500MB will be something of minutes to download - and a little bit longer than that minutes to 'install' it after the download
thanks for your suggestion.
it is an interesting assumption, and i really hope it worked that way.
after 2 hours update, eventually i found out that this computer no longer work on network browsing..

reading from another forumer at pclos gnome forum, i tried his suggestion of reinstall nautilus and the computer now regain its old working on network browsing...

then on second computer , i installed that PCLOS 2010 gnome, just as the first computer, totem player does not have sound,
so i proceeded with similar update, but this time i applied your method of running test and pick the fast one.. so end result is, it is just faster, far from being a minute. it took one hour !!, nevermind, after that, totem did not have sound!! and nautilus could not browse network..
so i tried second time without success. too bad, better gave up on second installation.