Kosumo, all you have to leech is the client, which rocks in at around 100KB.
http://www.guildwars.com/support/downloadclient/It will then download game content in the background, and as you enter new areas, which can sometimes be slow but is very convenient.
Using this method I reinstalled GW earlier this week after over a year of inactivity, without using any of my original game discs (hell if I know where they are anymore). Just had to remember my account email and password.
Guild Wars has always been very generous and flexible using this method. Still fun after all these years, and plenty of people still playing. Can't ask for much more for a one time $50 payment that I made in 2005.