I am sure there is a simple solution but I cannot wrap my mind around this.  When I create a new opportunity in my sales pipeline I have added additional fields to collect all the information provided by the customer regarding the project they call contact me about.  

One field I would like to add would be a field in which I can select the products required for the job and add the quantity needed, from the products module, just in case I cannot generate a quote right away.

Any suggestions would be appreciated.