raid 5/4 disks vs raid 10 with 4 disks

We are rebuilding a database server and need to increase performance. we were told to go to raid 10 take off the os/transaction logs to a mirrored drives and to keep the raid to 4 drives. Current setup is raid 5/4 disks, non mirrored for os. Question is,
Raid 10 with 4 drives is going to have a major increase in performance over a raid 5? or should we get more drives for the raid 10.