A note about the streaming technology. A change in the gameworld that you will download is no different than you downloading the data of a person who just logged on next to you. Or several people. I am pretty sure they arent going to change an entire section of the server at once, which is why they call it streaming. Even if alot in a city or something was being changed it might only be changed one thing at a time to avoid lag.
And while it actually might seem like a lot, the designation of what things look like takes a relatively little to send over a network connection. A lot of people do not understand how a server works, so they asume that the server is doing most of the work for their game, and that better graphics has to = higher server load (it dosent, just to let you know). This is where I think most MMORPGs can convince alot of their customers that their game is worth it. Granted, you are going to lag some with a dial-up connection, its unavoidable. However, you are only going to lag about as much as you would in d2 (network lag).
Of course, you have to add in that the game graphics will require a better machine on your part, so if you lag all the time (I mean like, all the time) then its undoubtedly your machine... or I suppose possibly your ISP has REALLY dropped the ball.
I work on/with computers for a living, so I like to think I know what I am talking about when it comes to that field. Of course, if you know something that contradicts what I've said, go ahead.
In any case, all that anyone REALLY needs to know is that GuildWars = awesome. And does not = d2. GuildWars > d2 ^^