There are different ways to measure performance, and you have to understand what they are and how they relate to the type of performance you are looking for.
Transfer rate - how quickly a large file can be moved to or from the drive. Important for copying large files or running programs that have to access large files (ie, Photoshop reading RAW picture files, video editing, etc.) RAID 0 can increase the transfer rate, so choose this if that's the most important thing for you.
Access Time (also known as "Latency" - how much time it takes from the time an I/O is requested until the data is delivered. Important when you need to read a LOT of files, such as when booting the system, loading applications, or running programs such as a browser which use files for caching. RAID 0 doesn't reduce the access time, so the VelociRaptor will be the better choice if this is what's important to you.