I bought Corsair Vengeance for my m17x r3, and I'm pretty sure that 90% of the people that swapped ram out are using the same. You can find them on amazon.
And yes you can do it by yourself, it's pretty easy.
Yeah windows 7 home premium only recognises 16gb. Pro and Ultimate recognise the full 32gb but 16gb is plenty. I wish I new that when I purchased my alienware. As I would of stuck with home premium as I have USB key for reinstalling windows home premium and it backs up all your stuff if you plug in an external Harddrive and puts it back on when you reinstall operating system. Good little bit of tech but its sitting in my draw collecting dust as I went for pro to use the full 32gb but I don't need that much ram. Should of done my homework lol. As alienware won't ship me one with pro on as it was only for use with my xps I was rudely told by rep and I don't have it as I part exd it for my alienware. Their mad told them I would pay shipping but still no