It depends on who the owner is. If you have drwxr-xr-x permissions on a folder that is owned by you, then you do have write permission.
Do however bear in mind that these permissions are virtual. They only exist while the filesystem is mounted, because NTFS does not support POSIX file ownership and permissions, and so the kernel has to emulate them at mount time.
More information about how permissions work can be found in the tutorial below. 
In addition to the above, you must disable fast boot — or hybrid boot, or whatever Windows calls it — in Windows, because it does not properly shut down the filesystems and leaves them in an open state. This in turn causes the kernel to regard them as damaged and it will thus mount them read-only so as to prevent further corruption.