Photosmart 7760 VS Photosmart 7660 VS Deskjet 5652

Hello!
I have an HP Deskjet 6122 printer and the photos quaility is quite
good. The only problemis that can't print A4 without borders.
So, I considered to change printer and as I bought adigital camera
recently I thought about an HP Photosmart.
As I can see, considering what I can afford, I'm thinking about
Photosmart 7760. But I have some questions about this subject:
1º Is this 7760 diferent of 7660, considering the printing quality
(then 7760 is fater than 7660, 12 to 19 ppm, but the printing
resolution is the same, I think!)
2º Is it different the printing quality of a deskjet to a phototsmart,
considering that the resolution is the same, I know that a deskjet is
8 mb cache and a photosmart is 16 mb, I meanm, faster... But I'm more
consecerning about the qulaity and the time that the photo will
mantain instact wit time....Like I can see, the Deskjet 5652 is 21ppm
like 7760 Photosmart.
The 5652 comes with full duplex module, and Photosmart doesnt!
What about the inks consume? I 've seen that Photosmart has more inks
to use and are less expensive but little also! So, will it be economic
to print all witlla photosmart, compared witha Deskjet 5652?
So my final question is "what is the difference about Photosmart 7760
and Deskjet 5652. Quality?

Love, Andrea