From some experience trying to interface with MS-SQL 2000 with Perl, these are the things that I've discovered..

MSSQL::* libraries don't work from Unix.. I may have looked at an outdated version of the pages, but this page is what I saw and it wasn't very encouraging about working on Unix, or getting these libraries to work with SQL server 2000.

DBD::ODBC as mentioned above, worked well for me..I'd really not advise using something like DBD::Proxy, although that is indeed one option, because of the potential heavy traffic... instead use a Unix ODBC bridge such as iODBC in conjunction with DBD::ODBC... it may not be the fastest, perhaps.. but on what I implemented, it survived a load test of 150 concurrent users with no problems..
HTH