Friends have complained they have bought Maxtor harddrives and they have died just before or after the warranty period. Others I know also have suggested similar issues. Although im not saying there a bad company as others may have had luck with their drives, me personally went for a Western Digital there harddrive seem to be reliable and have bought theirs for years.
As for the type of drive it really depends what you use it for, if you download or upload a lot of files, i.e. mp3's, you possibly require a larger storage so go for something like 80Gb -120Gb but if you are a heavy downloader you probably need a greater capacity. Windows and a lot of applications require some amount of storage so naturally go for a decent size so you won't be forced to buy another one in a few years