Hi Judy,
A new site indicates a new directory database.
If you have a seperate sql-server or instance for this new site, why not?
As a matter of fact, we're running 1 site on w2003sp2, sql2005sp3, and have installed a proof of concept site on w2008r2x64, sql2008r2x64. two different sites, same (windows) domain, 2 sql servers, 2 directory databases. Very nice to test intersite move-archive functionality ;)
Regards. Gertjan