i havent heard of any mechanical hdds that are capable of exceeding sata150s bandwidth (150mb/s) (burst rates aside). but if and when the 15k raptors are introduced next summer (or ssds start drastically increasing their STRs), the sata performance situation might change... and at that point sata300 (300mb/s) may have a reason for being included on mobos and even hdds.
until then though (or until we see how the 334GB platter seagate hdds perform in a few months or so), raptors will still offer top overall performance on the desktop from a relatively affordable sata standpoint, and theyre only running on sata150 too.
You need to know the difference between burst speed (which SATA has been bragging about) vs. sustained speed (which is the one you should worry about). Sustained speed is around 66mbps. Give or take. It's the same as IDE. You can run some benchmarks on sustained speeds on SATA & IDE drives & see for yourself.
OEM Drives have less warranty and come without cables, mostly in a white box or a bag.
You can buy an OEM drive and have no problems at all. But it has been proved that they fail more than the retail ones. They are cheaper, but not for a lot, so I would suggest to get a retail drive. Seagate or Western Digital, and you are good to go.
yes, its backwards compatible. i believe by default sata300 hdds have their jumpers set to sata150 to allow compatibility with sata150 controllers. you wont get a performance boost by switching the jumpers to sata300 though, but you will remove the compatibility thats there. IF the jumpers are set up that way by default anyhow. i have no personal experience changing jumpers on sata300 hdds for compatability reasons, but i believe this is the case anyhow.
Will a sata 3.0Gbs(2.0) drive work with a motherboard that only has a sata150 controller on it?
SATA drives are supposed to auto-negotiate with the controller and run at whatever speed both of them support.
However, there are some older SATA chipsets that only support SATA-150 and also don't negotiate with the drive correctly. These are older SiS and Ali chipsets, and the Intel 865 chipset. If you have one of these chipsets, you will need to move the jumper on the SATA drive to force SATA-150 operation, as choirbass said.
Seagate ships their drives with the jumper installed, which forces SATA-150 operation by default. On these drives, you actually have to remove the jumper if you want to enable SATA-300 operation.
Western Digital ships their drives with the jumper removed, enabling SATA-300 operation by default. On the above listed chipsets, you have to install the jumper to force SATA-150 operation.
For other hard drives like Samsung and Hitachi, check the manufacturer's web site for the jumper specifications.