How to choose extended partition during install

I have Windows 7 using 3 primary partitions and decided i wanted to dual boot on seperate partitions with PinguyOS.

I'm aware with some installations of Win 7 that you are limited to 4 Primary partitions but could not work out how to find out if i am also limited so decided to be safe and use an extended partition.

During the PinguyOS Install screens i could not find an option to create an extended partition using the free space, it just offered Logical and Primary.

I saw a video showing a guy first setting up a swap file as logical and then the "/"mount as Primary so i used this set up and all has worked out fine.

The funny thing is in GParted it shows it as an extended partition without me actually setting it up this way, which is fine lol but i hate not knowing why or maybe i am reading GParted wrong.

In Windows 7 it shows as 5 primary partitions but i'm thinking it does not read the PinguyOS partitions correctly, or my system allows more than 4 Primary partitions.

How do i find during the PinguyOS installation screens the extended partition option?

Watching a Ubuntu installation video which is basically the same as PinguyOS it shows the extended partition option alongside the Logical and Primary options in the same box, PinguyOS only showed Primary and Logical.

Thanks for all your help in advance.