There are any number of reasons that you might need to transfer the logins between instances of SQL Server. One of the most common times this is necessary is when performing a SQL Server consolidation or migration. The good news is that its a fairly easy task to perform for several generations of SQL Server.
VMware now officially supports running the VirtualCenter database on SQL Server 2005. As you may have expected there are a few caveats and a handful of configuration items you need to take into consideration. However, for the most part this is great news and will allow you to *finally* get rid of those SQL Server 2000 servers.