I have been investigating some hardware configuration to run a MySQL instance with a current db of about 100GB. I found that Dell has added bigger and faster disks to their PE2950 server line. The downside is that you can only run up 6x146GB 15k sas disks instead of the 8x73GB 15k sas disks. So you gain more storage, lose 2 heads, but the price is the same.
Then I thought of adding an MD1000 to the setup, but even though you gain a lot more capacity you have to shell out almost double the cost to just get started.
Since I am loading the box with 32GB of Ram I have opted to go with the 6x146gb raid 10 vs. 8x73gb raid10 for more storage since a lot of our db is going to be in memory anyway.