10GB You will receive no additional value at wholesale for larger hard drives. All retail machines are expected to have CD-ROMs thus there is no increase in the retail value. All retail machines are expected to have modems, thus there is no increased value at retail. If you have the drivers and instructions, this could add substantial value at retail if they are high end adapters. Operating systems are expected at retail thus they have no retail value.
Application programs can have significant value at retail.
If you have a newer machine for sale, we highly recommend visiting Ebay to view recent auction results of similar machines.