Joe D. is correct, there is no way to use SQL 2000 anymore because of the data type changes. The only way forward is to migrate the database to SQL 2005 or SQL 2008 by backing it up from the current SQL 2000 database and restore it on SQL 2005 or SQL 2008.
You mentioned that you have Plesk, maybe your version of Plesk only supports SQL 2000, but if you have control of the server you can install SQL 2008 Express on the same server even if you have SQL 2000 running on there because you can install multiple instances of MS SQL.
I asked for feedback from people using SQL 2000 way back in March 2010 and while a few people said they were using it they also said they could migrate to a newer version.
then we finally did drop support for SQL 2000 as of mojoPortal version 126.96.36.199 in July 2010
So we tried to give a lot of advanced notice to avoid troubles such as you are having now, but ultimately it was in the best interest of the project to drop support of SQL 2000 so that we could have a single data layer that does support SQL 2005/2008/SqlAzure.
SQL 2000 is legacy technology no longer supported by Microsoft and most hosting companies have offered newer versions of MS SQL for a very long time. If your current host does not offer SQL 2005/2008 then the only solution is to migrate to new hosting.