RAID 0 (Redundant Array of Indenpendent - or Inexpensive - Drives/Disks) is striping data across two or more drives, with no redundancy. RAID is a misnomer for this array, probably should be AID 0, but what can you do?
Your understanding regarding a striped array with two drives is correct: it performs quicker than just using one of those drives.
Cut and pasted from elsewhere:
"Since the data is spread out over multiple disks,
the reading and writing operations can take place on multiple disks at once. (My bold and italics). This can speed up hard drive access time significantly. Multiple hard drives may not improve hard disk performace as much as multiple processors may enhance the CPU performance, but it is based on a similar logic."
You could read these for more information:
http://www.tomshardware.com/forum/43125-32-raid
http://www.tomshardware.com/2007/07/02/raid_scaling_charts/
http://www.tomshardware.com/2007/08/07/raid_scaling_charts/
"I want a
redundant array of independent disks striping data across two drives for speed, so don't give me any
redundancy!", is what some are asking without knowing it when they ask for RAID 0 on two drives. If you're aware that you're getting zero redundancy when you run RAID 0, then that's good.
When something goes belly-up with RAID 0, the array fails, all is lost.
At the very least, keep another non-RAID drive for backing up files. It is not uncommon to have 2 x 160-320GB drives in RAID 0 with another 250+GB drive as storage. Or if you do have 3 identical drives to start with, go with RAID 5 if you prefer.
I'm assuming you've got a bit of an idea about setting up the array in BIOS and loading the drivers for your operating system when you install it.