So I stumbled upon a site where a fellow enthusiast was nice enough to create a program to update you Windows Phone from any version up to 7.8
I have a Sprint Arrive and after running the program 7 times (you have to do it for each step of updates that you are missing (F U Sprint) as I was on 7720 beforehand.
Remember he will say and I will say, if you mess up your phone we are not responsible. But the success rate based on the comments on his site have been very good.
Install WP7.8 via WindowsPhoneHacker