In order to do RAID through SATA, the interface bus must support RAID. This means that you need to get a SATA PCMCIA card that has a RAID chip. I was unable to find any that met this criteria.

As far as extreme performance goes, I can't imagine that you could get extreme performance by first going through the PCI bus, then through the PCMCIA bus, then through the bus on the PCMCIA card, then through the drive. I was unable to find any benchmarks, but I would believe that the sustained data rates through an IDE channel would be higher than through PCMCIA.

Laptops are designed for ease of use over performance. If you are wanting insane performance, custom build yourself an ATX machine with all the bells, whistles, and tricked outness. It definately sounds like you have money to blow on this concept, so I don't know why you would try to pimp out a laptop rather than just building a high-performance desktop that would offer superior flexability and performance at a lower cost and level of frustration.

Actually, it's not a bad question.

This question is 'old' (from 2005), yet it comes up almost first in a Google Search for the same topic.

An old laptop can provide excellent benefits:
- Lower power consumption*
- Compact design to fit in a small (ventilated) server cabinet
- Lower noise

I was messing around with the idea of running RAID on my Desktop's SiI3112-based 2-port PCI Sata card. I found updated flash bios for the card. The similar 3112-based PCMCIA card I found does not have this. Without hardware card RAID support, one can do a software-based RAID (mirroring) array in Windows XP, yes, for additional storage once the computer is running. This RAID array could not be bootable though, unless the PCMCIA card contained boot bios code.

While current laptops, some, offer RAID, the idea is using an older laptop with no more battery life, to function as a low-power server.

*Compare this with a super-locked Athlon XP 2600+, and a Shuttle NFORCE2-based board Desktop. Runs a modified XP, Apache2, eMule, uTorrent, Dyndns.org client, and several terminal server sessions. Works great inside a double-walled steel case (from a quality office Fujitsu Siemens), only problem is: NFORCE2 does not support the powernow management of an AMD Athlon XP 2600+, or so I've read (I could be wrong). Box always runs at top speed, and uses the maximum amount of electricity. Whereas a laptop, by definition, uses less electricity at least when idling.

Focusing back specifically to the original poster's question of adding a RAID array to a normal-use laptop, the Western Digital MyBook World Edition II offers RAID mirroring, supporting 2x 1tb drives, in a tight-looking case, offering several possible connections (I think USB/Ethernet and maybe Firewire or Sata) This unit costs about 400-500 USD.

Google for some articles. I found this one: http://martin.hinner.info/mybook/

If you are trying to save the maximum amount of money, though, and do it on the super-cheap, with two external eSata drives, then software mirroring in your Operating System is the way to go.