I always thought it'll be hit n miss whether or not my 6800GS (overclocked a fair bit) will be able to cope with the game on the lowest settings - but all this nonsense has pretty much sealed it really.
I can start downloading it in 6 minutes, so I'll find out tomorrow if well my PC can run the game, or if it can at all.
If not, new graphics card time me thinks. 'tis the bottleneck. Probably get me a HD4670 assuming all the issues with ATI cards are fixed by then.