ok if it's not in the MBR you'll have to make the partition bootable or "active". you're saying you have no fdisk in windows or your linux distribution?
well if you made a boot disk and can get into your linux system, log in as root and run /sbin/fdisk /dev/hda (or whatever device you installed linux on. mine is hda) there are many options to it. i think b is the bootable option. anyway, once you run the fdisk command you can type "m" for help and get the correct option to make your partition bootable. just remember to use the "w" option to write the changes to the disk before you quit!