IBM/Hitashi DeskStar series are quite sensitive to heat, so if you're trying to jam 4 of them into a $200 eMachine, have fun RMA the HDs. No wonder Apple use Toshiba HDs on their iBooks, PowerBooks, and iPods.
I have a pair of IBM 30GB 75GXP in RAID 0, an IBM 120GB 120GXP, and a pair of Maxtor 20GB D740X-L also in RAID 0. Also have a pair of WDSE 120GB/8MB coming in. Been running them for 20 months, 18 months and 6 months, respectively. The thing is I don't use them as primary HDs, only has secondary file storage. Plus, they're all well ventilated in an Antec SX830 and SX1030 series case, w/ 80mm fan blowing on them.
Right now, I'm using Maxtor Plus9 160GB/8MB as the primary HDs on the PCs systems (2). I also have a G4 dual 1.25G running a WDSE 40GB/8MB as primary.
A lot of people say Seagate makes the most quiet HD, never tried them, so I can't confirm. From experience, IBMs and Maxtor's have the lowest dba, WDSE w/ the highest.