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I'm trying to install Ubuntu 12.04 alongside windows 7 on laptop,
The HDD is 750GB,  windows is installed on /dev/sda2 with roughly 290 GB
there is a seperate D: drive  /dev/sda5 435 gb,
/dev/sda4 is  25gb containing win7 for recovery process
/dev/sda1 is roughly 109MB saying it's a win7 loader,

I wish to install Ubuntu 12.04 it on the 435GB partition, after clicking install along side windows,
in the selected drive it shows my HDD. sda -750GB hitachi,   then says 431GB a little further right, so I assume this is my /dev/sda5,

but beneath when allocating the drive space by using the slider it has
split the drive into equal 217GB portions, if I slide it to the right
all but 29GB remain. either way I slide it,   leaving 405GB remaining,

WHAT is the 29GB left over?  which way do I slide it ?

  In the advanced partition menu /dev/sda5 is 435GB
why is there 29GB left over in the previous drive allocation menu,

   should I use the partition editor to format
/dev/sda5 to ext4 or not ?  thanks for your time.