Hard Drive And Raid Setup

I am currently in the process of upgrading my web/mysql server due to heavy loads and io waits and have some questions. I am trying to be cost efficient but at the same time do not want to purchase something that will be either inadequate or difficult to upgrade in the future. I hope you can provide me with some guidance.

This server is a Centos Linux box, running both apache and mysql. The current usage on the box is:

Mysql Stats:

50 mysql queries per second
With a ratio of read to write of 2:1
Reads are about 65 MB per hour and writes are around 32 MB per hour.

Apache stats:

35 requests per sec

The two issues that I am unsure of are:

- Whether or not i should go with Raid-1 or Raid-5

- Whether or not I should use Sata Raptor drives or SAS drives.

In either configuration I will use a dedicated Raid controller. If I went with SATA, it would be a 3ware 9650SE-4LPML card. If I went with SAS, I was looking at the Adaptec 3405 controller.

Originally, I was going to use 3 x 74GB Seagate Cheetah 15.4K SAS drives in a Raid-5 config. After more reading, I learned that raid-5 has a high write overhead. Though read is definitely more important based on my stats, I don't want to lose performance in my writes either. With this in mind, I looked into doing Raid-1 instead.

I came up with these choices:

- Raid-1 - 2 x Seagate ST373455SS Seagate Cheetah 15K.5 SAS. HDs & controller costs are $940.

- Raid-1 - 2 x WD Raptor 74GB 10K SATA 150. HDs & controller costs are $652.

- Raid-5 - 3 x Seagate Cheetah 15K.4 ST336754SS 36.7GB. HDs & controller costs are $869.

- Raid-5 - 3 x WD Raptor 36GB 10K SATA 150. HDs & controller costs are $631.

As you can see we are not looking at huge differences in price, so I would be up for any of these options if I could just determine which would give me the best performance. I also know that I should have a 4th hotspare drive, but will buy that later down the road to ease cash flow in the beginning. If I went the SATA route, I would buy the 4th immediately.

From what I can tell, both configs provide the same redundancy, but are there any major performance considerations I should take? From what I have read, scsi/sas can enable database applications to perform better do to a lot of small and random reads and writes?