The 3ware 7500-4 works perfect with 5.5 all you have to do during the install is to add the driver. There is a keyboard combination that will stop the install to allow you to add the driver from the 3ware disk. My server in the office has 4 IBM 120GB in RAID 5 in e-smith 5.5 with a 3ware 7500 card and Onstream 120GB. The 3ware card is available for $245 and the two port for $119. If a card fails you can plug a new card and keep going.