Which campaigns does the client install

Does the client from www.guildwars.com install Prophecies only, or factions only, maybe both, or all three? Anyone know the answer on this question?
it takes very long to load the game. Thanks in advance, Fluim

I think it depends what is on your account.

The only thing that will definitely be downloaded from all games will be character models, armours, weapons and skills, as well as backend and frontend code (like the UI) since the game allows travel between continents for those that have that campaign.

As for maps:
All PvP maps should be downloaded.
Tyria will be downloaded if you have Prophecies on your account
Canthan will be downloaded if you have Factions
Elona will be downloaded if you have Nightfall (This be the big one!)

They are all downloaded together, you just can't access the campaigns you don't have an access key installed for.

The best bet may be to download everything once to get started then you'll only get the new/changed things after that. Make a copy of the shortcut to GW to something like "GW Update" then do right-click > properties. Add "-image" to the end of the line that runs the program, something like:

"c:\program files\guildwars\gw.exe" -image

Then when you run that it just sits at a status screen updating everything. Let it run over night.

As greenc27 says, they are all installed into your machine. The access to the content is granted with the Key codes that you get when you buy each chapter. Note that when you buy factions and Nightfall both will add 2 spots to an exsisting account. If you have one chapter then you should have 4 spots 2 chapters 6 spots and all 3 chapters gives you 8 spots.

Mega Mouse

And if you got the pre-release of Nightfall you'll get an extra spot, so I have 9 Slots