open source database visualization

[Christopher Chisholm]

Hey Everyone,

Does anyone know of any open source or freeware project that can graph 
relational databases?  I'm thinking of something similar to the way MS 
Access draws tables, or similar to Visio. 

I don't need the program to be able to read the contents of an existing 
database (though that may be nice).  All I really need is something very 
simple that lets me create tables and specify key constraints.

I'm running Windows, and while I have access to Linux boxes it would be 
a lot easier to have this on my desktop.

Thanks!

-chris