Hi Matic,
My favourite tool, Polychop is an excellent free Max plugin that allows you to retain texture coordinates and lock selected vertices.
http://www.cadalyst.net/extras/plugins/Modifiermax5.html
Search the page for polychop
Its also available for other versions of max
We also sell a good polygon reduction tool called Action3d, look under the 3D Modelling tag at the top of this page.
Nvidia's melody also has a mesh reduction facility, its free, although I've had plenty of problems with it
You will probably want to clean up your mesh manually after reduction, but all of these tools are a good way of quickly reducing the resolution of a model.
Regards