First thing to do is to make a disk image of your entire SSD using something like Macrium Reflect Free Edition (Windows) or Clonezilla (Linux). If you use Macrium, you also need to make a bootable rescue CD/USB. Similarly, Clonezilla should be run from a live-CD/USB. You now have a backup of your current system and a means of recovering the disk to this state if something goes pear shaped when you try to change your partitions/boot system.
sda1 is almost certainly your factory recovery system for reloading Windows in the event of a catastrophe. You probably want to leave this in place just in case you ever want to go backwards. It's only 100 MB.
Now you can use a live-CD/USB with Gparted and remove sda2, your Windows partition. Once this has completed, you could expand the extended partition into the (now) unallocated space if this what you wish.
At this point, I would suggest re-installing the GRUB2 bootloader using the following commands in a Terminal window:
sudo grub-install /dev/sda
If there is any problem booting, try an alternative method of recovering GRUB (e.g. http://linuxnorth.wordpress.com/2013/01/09/re-installing-grub2/)
If all else fails, remember that rescue disk/disk image...?