as long as you have the windows partition mounted as read-write, you can copy back and forth. This is the default if your windows partition is FAT32. If it's NTFS rw is available, but, afaik, still experimental. I don't know for sure if it is enabled by default, but you can edit your /etc/fstab for the partition and remount it.
Windows, however, can't recognize most (any?) Linux partition formats, so you can't read or write any linux files from windows.