Fireworks and Photoshop are definitely not good for this purpose.

What I'm looking for is a simpler (cheaper) option for MS Visio 2007, this one really rocks.

The sites are built by myself.
I use the models both as a guide to myself (good systems require good models) and to discuss the overall thing with the client before starting to code (usually I use a simpler version for this).

For DB modelling I use MySQL Workbench 5.0 OSS.

Thanks!