Question about Factions and Prophecies...

Okay i just decided that i was going to get GW so i went to the store and i was looking for Prophecies, but they only had Factions and Nightfall. So anyway i decided i would just get Factions. Now here is the question: If my friend (who also wants to start playing) buys Prophecies can i download the game onto my computer and then use the account that i already to have go to the other land and could he do the same thing by downloading the Factions that i have?
So in other words instead both of us buying both games we each buy one, but then we can download the one we did not buy, but still have acess to both of them.

Thanks in advance

No, when you buy the game there is an access key, and to put the game on your account you need to input the access key. Each access key can only be used once, so unless your friend is planning on not using the access key to Prophecies you can't add it.

Sorry about that

Everyone can have download all campaigns. It's the account that you need, not the Guild Wars exeand .dat.