I tend to agree with others. EXAMPLE: Just because you have a 200mb db and split the data up evenly (or so you think) into 4 50MB data files on 4 different luns may or may NOT help you. You have to remember that 3 of those 4 50MB data files may have mostly static data that is hardly used and the 4th file may have mostly one large table that is read, inserted to and deleted from heavily. So, you might do all of this work and get very little bang for the buck.

Your best bet is to find out which specific dbs are the most heavily used and what times of days they are and simply backup/restore them to a different drive/lun.

Also, if you run Update Stats and Integrity Checks on a regular basis make sure they are running during the most quiet time of day. The integrity check job is VERY I/O intensive.