How to repartition my drive for dual booting Ubuntu and Windows

In order for your older BIOS to find your kernel, it must be within the 137GB limit, which is the first 137GBs. Your current setup has the only ext3 partition much past this. As others have noted, you are really going to be space-starved once you get to the Ubuntu install anyway. My suggestion is to shrink the size of /dev/sda1 by 15-20GB, and make a /dev/sda3 which is inbetween /dev/sda1 and /dev/sda2. This should be your new root partition for Ubuntu.

Shrink your /dev/sda5 -ntfs 167.59GB with at least 10 gygs and add it to /dev/sda6. You can use any partitioning tool to do so, partition magic is handy.