joining ADSL connections

is it possible to join multiple adsl connections into one large connection?

for example 5 8mb ADSl connections will be one total 40MB connection.

if we can how do we do it?

ps: usually for company type of 50 computers network setup. is it recommended that we use a server computer to act as a server, or is it better to have a “router” to act as a server (to provide internet connection)?