Reverse Engineering A SQL Database

Ok, this is something I've never done. Now, I need to do this as the database i have to work with (created by someone else) is unreadable. No naming conventions, no relationship diagrams, i mean, i don't even have any specs to look at.

So, Visio will do this, however, in my employers infinate wisdom, they only got the standard edition, which doesn't support database mapping.

I have found something called SQL Edge which i can download. Has anyone used this? Is is as good as Visio?

Are there any other programs which will do it for me?

Or should i fight the case to buy Visio Pro ?

I appreciate any ideas!