Biztalk Server 2006 64bit problem

Biztalk Server 2006 64bit problem

I am trying to install a 64-bit biztalk server 2006. However when I start my installation it asks if I want to get my .cab file from the internet or install it manually etc. Because of internet security issues here at our work we can't get it from the internet directly. So I downloaded it manually: BtsRedistW2k3EN64.cab, to be exact.