It works faster than the hard drive. Get as much as you can and make sure that your system has open memory slots for further use to add more later. A customer that is on a budget should probably sacrifice things that are unnecessary and focus their attention on speed and storage capabilities. It is less important to have a 21 inch monitor than having an efficient computer system. The best printer for most people would be the inkjet.
Laser printers are only necessary if the user needs a fast nearly type set printer.
Inkjet printers are much better at color documents and are significantly cheaper. A higher dpi is usually better unless the lower dpi model has enhancements to make it look more sophisticated. Now, you should be completely ready and excited about going to get your new system. There are a lot of considerations to take into making a good decision. Try not to get too frustrated, there are many people that can help you get through the process safely.