The disk management console will tell you the location of the partitions on the disk, left side of the bar is the outer edge right is inner edge.
Every model of drive is different some lose thoughput as soon as the head starts moving further in some like the F3 hold max performance for a while before the performance drops, on a F3 drive the max size of the partition with 2 drives in raid 0 without access speed drop is soome where between 50-75GB (8,1ms-8.8ms) i did'nt test in the middle, because i am only interested in creating a minimal partition for windows. The partition you could create before increased access delay is half the size with a single drive then 2 with 2 drives in raid0 because in raid0 you're spliting the partition between 2 drives.
The way i tested what i did was lock the RAID array to the desired size i wanted to simulate a simple partition if i had created just a partition i would'nt have been able to test what i had done because disk benchmark programs i have seen don't take any notice of partitions and read the entire disk.