Hard Drives

I need a decent new hard-drive, not external. I have a few spare bays and i was browsing some sites (newegg, tizer etc) but having not kept up with advancements with HDD's; i am swamped by the variety of different options.

Is there any commerically viable HDD's that have an RPM faster then the average 10,000?
SATA 2, much better then IDE?

Thanks anon, i know its not in your nature to be helpful and i expect my fair share of bullshit but my gratitude to those helpful posters.

>>6
Single disks seem risky. If one disk fails you have none left, right? This seems a rather big sacrifice for not knowing a fucking thing about RAID.