The hard drive is the storage unit of the computer. All information is kept on the hard drive, so the more data you plan on storing, the larger hard drive you should get. If you are a basic user that simply stores pictures and text documents, an 80 gigabyte hard drive will be more than enough, although you may want to consider a 120 gigabyte hard drive if you have a lot of pictures or music. If you store a lot of movies or music on your computer, we recommend at least a 200 gigabyte hard drive. The 400 gigabyte hard drive will ensure you wont have to worry about space for quite some time.