Connections to SQL server

[AMP]

I have an application that runs at various sites, each with thier own
SQL servers, how can I change the connection in setting, depending on a
value in the registry

for branch1 it would be

registry localmachine/software/application
server="Branch1 "

the connection setting will then be "Data Source=Branch1; Initial
Catalog=databas e1,Integrated Security=True

for Branch2

registry localmachine/software/application
server=ThisBran ch"
the connection setting will then be "Data Source=ThisBran ch;Initial
Catalog=databas e1,Integrated Security=True