list of components
Optical drive (cd/dvd drive basically)
Heat sink fan(keeps the cpu cool)
wireless/ extra usb ports/ extra lan ports/ etc....
There are basically two types of cables used in mainstream computer builds the IDE cable and the SATA cable. The IDE is the old standard and is the fat thin wire that is about 2 inches in diameter and so prohibits airflow. SATA is the new standard it has faster data transfer although not fully utilised because mechanical parts cant move fast enough but the wire is thin about a centimetre in diameter and allows for allot better airflow
You can either use the disks as seperate disks which are not related in anyway or use a raid configuration. RAID0 (needs at least 2 harddrives) is where multiple harddrives have the information spread between them and the multiple physical drives are seen as one by windows this increases speeds but if one hardrive fails you lose all the information as it becomes incomplete. RAID1 (needs at least 2 harddrives) Is where one drive automatically copies all the information on the master drive making all your data secure in case of harddrive failure the limitation is windows can only see one harddrive so you cant add information to the backup harddrive in a raid1 configuration. RAID5 is a cross between RAID0 and RAID1 and requires a minimum of 3 harddrives these stripe the information between them but also if one hardrive fails the 2 remaining hardrives can rebuild the array with the new hardrive preventing data loss.
This may seem a little complicated but trust me it is all very simple and everyone on here will help you every step of the way