I think you've got the math a little messed up. The accusation was made in 2008, yet the resolution has been reached "After five years legal sparring" Given that it is only 2012, even if the accusation was bade in the beginning of 2008, only four years have passed.

Wonder if they'll have to pay back a large chunk of that cause of all the invalidated ones?

They probably wanted both parties to look like winners, regardless of who lost what so they made the settlement confidential.

Rambus still had the opportunity to appeal the decisions. If Rambus's source of income is cut off due to the invalidated patents, what do they lose by doing so?
Simple economics might say to Nvidia that if the cost of renewing the patents (bound to be much less than before the judgement) are less than the cost of ongoing litigation with Rambus, then why not settle? The patents/settlement concern DDR3 (and presumeably DDR2), so this really only affects entry-level graphics and maybe legacy chipset support...both of which are rapidly heading the way of the Dodo....as is hopefully, Rambus itself.

No problem. Easy enough mistake to make, especially since they made a five year agreement.

I am astonished to see that how many people abhor something new with out even trying it, perhaps it has something to do with 'fear of change'. Anyway, any UI as long as it allows users to customize itself according to their taste shouldn't pose any problems, e.g. I never really use 'Start' button, but I can create shortcuts according to my needs, hence, it never really get in my way either.