Remember you need only the "Base" and "Textures" packages to run Orbiter. Everything else is optional. Select a download mirror close to your location, and if necessary, try several (try to avoid the medphys server, because excessive demand on that server will get me into trouble ;)
If you have a slow connection, you may try at a different time of day when net traffic is lower. A download manager may help as well. Please note that I am not able to provide a CD distribution service, although Orbiter occasionally features on magazine cover discs (so this may be your last option).