Using something like the fun classroom is it possible to fill the classroom with one high resolution character and the others using low resolution characters. I doubt my computer could handle 7-8 high resolution characters in one scene?

Don't see why not. Such characters would be background fillers and not draw any attention from the main aspect of the render. Whatever it takes to get image rendered the way you want it without costing computing overhead.

Can you point me to any low resolution characters for sale? Is there a way to know if a character is hi rez or low rez?

I'm finding the best way to handle this these days is using billboards. Set up your scene lighting and camera angles, put in a subject you want, then delete everything but the character (and desk if you need it to interact with it). then render it without anything else in the picture. It should be really quick. You will use this render and an opacity map to texture a plane. You can put as many of those in a scene as needed without causing any overload problems for the computer - they are 2D. You can also rotate the camera around the subject and take multiple shots for future use building a library. If you take a look at some of the products RiverSoft is doing over at DAZ, that's exactly the technique he is using, and it makes doing crowd scenes a breeze. You can do scenes with 100's of characters this way, and they are all "high resolution" quality.

Riversoft's products are the "Now Crowd" series over at DAZ if you wanted to take a look at the technique. I make a lot of use of them as well as creating my own.

Edit: When doing the rendering, output to PNG - that will give you a transparent background but leave the shadows from the render so it will fit in with the lighting of the scene.

Billboarding is an excellent way to render crowds without the memory overhead. If you are still interested in lorez figures, DAZ3D does have an entire series of animals and the Lorenzo and Loretta Bundle which can be used in Poser.

Sorry for the delay but I was away for the weekend. Thank you for the information about billboards. I will start learning to use them as they certainly sound like the answer I am looking for.....

Here's I scene I did with 10 characters in it - all billboards. 3Delight render. It works the same way in IRAY

Here's another one. The girl in orange at the front is 3D, all the other people (20 I believe) are billboards.

I found a 32 page pdf on another site that teaches how to make and use billboards for daz studio. All I did was Google the phrase making billboards for daz studio pdf.