Can I change Read and Write Permissions?

I'm trying to get as much of my old Windows stuff onto my iMac.
It's all stored on a Seagate 300GB External HD that is partitioned 150GB Mac and 150GB Windows NTFS. I can see and copy Folders and Files from the Windows Partition, but cannot delete once copied, this is very inconvenient as it means I have to keep unplugging the hard drive from the iMac and plugging it into my MacBook Pro (with Windoze installed) to remove the Files/Folders I have copied onto the iMac. Does anyone know how I can change the read write permissions on the Windows Partition so that I can copy then delete off it without constantly swapping computers. Thanks