Just a point to note, Maxtor doesn't exist anymore, well in so far as drive manufacture is concerned. Seagate bought Maxtor, and now Maxtor is simply a brand name that Seagate uses for some of it's external drives. Crack open a Maxtor external drive and you'll find a Seagate hard disk inside.
Current major producers of 3.5 inch hard disks are Western Digital, Seagate, Hitachi, and Samsung. ExcelStor may still manufacture hard disks but you probably won't see many of them in the west as they are predominantly distributed in the Asian markets
Current producers of 2.5 inch hard disks are all of the above plus Toshiba.
However Western Digital are currently attempting to buy Hitachi's storage division, well they have bought it subject to various monopoly commisions giving the ok.
I remember when you could pick from around 20 different HD manufacturers. Conner, Quantum, Hewlett Packard, Sony, IBM, Fujitsu - all either gave up, or sold off their storage divisions.