i dont know if you'll have to download all the updates seperatley or not. when i got a new comp i had the game disks, but it took over 2 hours to download all the updates from release.
It would make more sense to download the client and have your mate burn hs guild wars dat file to a disk so when you start up the game and it starts to download up dates you can just exit it and replace you dat file with his hence saving you the trouble of a very long download.