material type

hi friends...

i want to know, suppose i have 20 computers at client, all the computer r of different configuration and are of different prices, and the ram , motherboard and other parts of computers are also available in stock.

i just want to know under which material type computers should come and should i have to create 20 different computer under that material type. and under which material type should the ram, motherboard, etc r considered...

please help me, hope my question is clear../

thanks in advance....