which is v7.0 SP5, MUST be installed on Windows 2003 (x32 bit). The upcoming release of 7.1 will have to be installed on Windows 2008 R2 (x64 bit). Currently, it is a best practice to have SQL on one box (on a 64bit platform, SQL 2005 x64, if possible) and the management platform on another.
Many things are going to change with the release of 7.1 from an architecture perspective. I do not think it was ever supported to run on SBS edition, standard\enterprise is preferred.
See the platform support matrix for further information.