Raid on a pc

The best way is to add a RAID controller card.
Preferably one that controls SCSI hard drives.

Then, depending on the class of RAID desired, you install 2 or more identical hard drives connected to the RAID controller.

From here, the exact process depends on the RAID controller and type of RAID desired.

Chas

you need more information before you attempt anything.

probablem with your question
there is no such thing as a "raid drive"
there IS however a raid array, which is 2 or more drives

you'll need a raide card, pci probably, promise technologies has some good stuff, i'm using two of their cards now.

best to get drives that are identical for best performance, after that, it depends on what you need raid for:
performance
redundancy
protection
backup?

You should also be aware that not all operating systems support RAID arrays. If you are considering RAID for data integrity then you should set up a mirror. If it's to gain the abilty to add drives as you get low on space, then use RAID level 5. Microsoft's web site and ZDNET both have good articles and how to's on the subject.
Avoid using any sort of software based RAID as it will slow things down.
I use Promise also and it works well with W2K. On my servers at work I use a RAID 5 SCSI array with 37.5Gig drives (6 of them).