furmark is now limited intentially on both AMD and Nvidia cards, it was NEVER an accurate performance benchmark and is a litterally worthless tool.
I'm not sure I've ever seen a Cinebench done on a gpu so I doubt its got any acceleration via Cuda/open cl, if it did someone would benchmark it at some point.
Realistically with 3d work you need to decide which 3d apps you'll use, go to their websites and check if either have gpu acceleration. A pretty decent CPU will likely be required either way, if it ends up being a program that only AMD or only Nvidia support, the choice is fairly obvious, if neither support it and its a program you have to use, go for as good a cpu as you can afford, if its something both support you'll want to track down specific benchmarks or look on the developers support forums as that will usually give you a very good idea which company is better supported/faster.
My guess at this point with little information would be Nvidia gpu and Intel cpu, really the best thing you can afford, Sandybridge if sub £400 mobo + cpu, hexcore i7 maybe if you can go for more money.
Depending on when you need to buy, AMD will be bringing out octo core Bulldozer chips in the sub £400 price bracket in 3-4 months it would seem that early rumours suggest, have INSANE Cinebench performance and could well be ridiculously good cpu's for heavily multithreaded cpu loads like rendering.
