Very slow raid 0 setup

[computerpro3]

I have a windows software raid set up with 2x 500gb western digital 7200RPM drives. I used to be able to hit over 100mb/s transferring files with the array, but now even when copying from one directory to another on the same array I get 30-35mb/s.

Any clue what is going on? Vista X64 Ultimate edition is my OS. There is 300gb free space.

EDIT: And when transferring files from the raid array to my raptor 150gb, it starts at 112mb/s and drops to 30mb/s where it stays.