You would be better off with one 240GB drive than 4 60GB drives in RAID-0.
RAID-0 has no fault tolerance so if 1 drive dies you lose all of your data. Also, your odds of drive failure are 4 times greater than if you have just 1 drive.
Also, you only have 2 6Gb/s ports. A RAID-0 array's performance is based upon the drive with the slowest Read/Write speeds. So your Read/Write performance would be based upon the drives connected to the 3Gb/s ports.
To get maximum performance of all 4 drives you would have to buy a PCIe x4 or x8 RAID controller card. Good cards start around $300.