Thank you for providing the iso image, but it seems this is not an issue of tools I am using.
I have downloaded multiple versions of Partition Magic, from UseNext. Plus this one, i have 4 altogether (by the way, this one comes with the identical serial number as the one I got from Usenext). They are all comercial-versions of PM. I installed the Powerquest PM 8.0 i downloaded from Usenext, it works well on my Dell laptop -- I can create a new partition over unallocated space; However, on my another laptop where dual-operating system installed, I could not perform the same operation, isn't that strange?? So, it becomes obvious that the issue is with the current partition status, perhaps I need to get rid of one primary partition(as 'redman' suggested)? I got 3 primary partitions associated with: /, /swap, /boot on linux; and 1 primary partition for winXP:
local disc C, NTFS, 43G, primary
(*) , Unallocated, 15G, primary
local disc(*:) linux ext3 , 102M, primary
(*) , extended , 36G , primary
local disc F, Type 8E , 8G, logical
local disc D, Type 8E ,28G, logical
local disc(*:), type D7, 1027M, primary
Any advise on solving this problem?
I very much appreciate your help..