Database Vendor Alternatives?

Does anyone have experience, recommendations or just plain opinions that might help me out?

We really need a high-quality, high-performance option for little to no money. (Boy, you could say that about almost anything couldn't you!)

Currently our organization is using SQL Server 2000. It offers XML streaming, DTS, and other advanced features. Not to mention, it's really easy to use and works well with other msoft products (Visio, Visual Studio, etc.). However, many of our clients are non-profit organizations so the price tag is a bit of an issue for them.

We've looked at, and used, MySQL. It seems to be a good alternative, but doesn't support nested subqueries and stored procedures - show stoppers for the kind of work we do.

Oracle has similar features to MS SQL Server, and we've used it, but honestly, we can't really afford a good full time Oracle dba at the moment and its not very developer friendly w/o add on tools.

I've started looking at OO database solutions as well, primarily Matiesse ( but I don't know where to start in that arena.

Well -
Any thoughts?

thanks
munkyCmunkyDU