Ah ha... I get it. OK... I can't find any 160.1 radiators, so do you reckon a 120.3 and a 120.1 in the same loop (with the high airflow fans) would work well enough in a single loop to cool dual GPUs and an OCd CPU? This would also probably be a good option for me because I doubt if I could fit a 120.2 in the 5.25" bays with my other drives - but I could fit a 120.1 at the back (as long as I didn't need big shrouds).
I also like the redundancy idea of the two pumps, so thats another plus for this giant system idea. As to the advantage of the 2 loops being lack of galvanic corrosion, it doesn't really matter because my blocks and rads are just copper/accrylic.
Just wondering, due to the high restriction of the CPU/GPU cards' blocks (EK supreme and 2 x EK 9800GX2), should I arrange my system like you put above, or should I go for something else? This I suppose really boils down to: if I put 2 rads together and then the CPU>GPU>GPU bit, will the last GPU be less efficiently cooled, or does the heat balance into an equilibrium for all of the loop? Sorry if that's a really beginnerish question

Also, I don't think I'll water cool my mosfet/NB/SB, because I don't really care about noise from the fans and my case has got quite a few already (I would have 3 120mm & a 200mm going in and then the fans from the 2 rads going out).
Thanks for the expert advice! You've definitely helped me change my mind for the better about my cooling setup