Splitting the site into 2 different parts?

I'm building a dental supply store...
it has 2 types of stuff....for technicians and for doctors
I want to split the categories box in 2...so that the if a doctor comes into the site...
he won't have to see all the technician products and vise versa...
The thing is that I can basically put the stuff in two main folders and the sub folders from there...
But then I'll have only 2 folder on the home page in categories box....
How can I achieve the splitting without creating another site and another database?
please guys I'm a noob and I need help
thanx in advance :)

Maybe start with two main categories: "Doctors" and "Techs" and make the appropriate sub-categories under each.

If a product is appropriate for both groups, cross-link them so it shows up in both.

ie:

Doctors
-> scalpels
-> funny pills
-> skill saw

Techs
-> rubber gloves
-> rubber noses
-> whatever

Or is that exactly what you -don't- want to do?