Yes dual boot is possible, even with an NTFS filesystem.
Refer to:
http//:ctdp.tripod.com/os/linux/usersguide/index.html
Read section 3, "Installation and getting started". Read the part under the header "Installing multiboot systems with Windows NT or Windows 2000"
There is also a Linux+NT-Loader mini howto available at:
http://www.linuxdoc.org
Basically, you can install the two operating systems in any order. It is helpful to have a utility for partition management such as Partition Magic. When Linux is installed, be sure to make an emergency boot disk, and install LILO to the pertition that you install Linux on, NOT the master boot record. The NT loader will install on the MBR.
Once installed, using the emergency boot floppy, boot to Linux, and make a copy of your linux partition bootsector, then make it available to Windows in a file called bootsect.lnx. Then modify the Windows boot.ini file to use the bootsect.lnx file.
Any time you make a change to liloand re-install it to your Linux boot sector, you must repeat the procedure to make your changes effective.