Increasing the System Reserved Partition has solved the problem, I made it as 650MB and all my partitions are primary and I've successfully installed Win 8 Developer Preview Version
Thanks to Bill2 and all the friends who have replied. Thread Solved
how did you actually solve your problem ? when I tried to install window 8 developer preview on separate , I had installation hang at 27%, I tried everything, but finally had to install in a virtual box.
now I have the 'does not contain enough space problem' with windows 8 consumer preview.
any suggestions ?