Don't buy 3ware SATA RAID cards
I was unfortunate not to do proper research when I ordered 3ware 8506-4LP card last year. I had nothing but trouble since. It takes forever to initialize so if you want say RAID-10 over 4 250 GB disk it would take about half a day. To be fair you can still work with the array, but the performance is going to suffer. I guess I was spoiled by 1 hour array rebuild with IBM ServRaid SCSI RAID controllers.
The worst thing about 3ware cards is catastrophic write perfomance. I could not get the card to write more than 6 MB/s. To add insult to injury just copying files from one dir to another would take the system load to 2. Many people have reported similar issues, its all over the web. 3ware people seem to blame everyone else but their poor design.