Well after much dithering I ordered my parts last week. I opted for a single very big IPS monitor rather than struggle with a triple monitor setup as I would then have had to buy another Graphics card and fight with SLI etc.
New PC is up and running
Silverstone Fortress 2
GeForce GTX 580 3072MB GDDR5
Asrock Z68 Extreme4 Intel Z68 DDR3
OCZ Agility 3 120GB SSD
Intel Core i5-2500K 3.30GHz
Corsair Professional 1050W PSU
Kingston HyperX Genesis Grey 8GB (2x4GB) DDR3 PC3-12800C9 1600MHz
Corsair Hydro H80 High Performance Liquid CPU Cooler
Hazro 27" Monitor 2560x1440 resolution
At the native resolution CLOD is smooth as glass with everything on highest settings and AAx2 but with Shadows off. The performance hit from shadows and their fugglyness isn't worth it. Clouds still drag down performance.
As my desk isn't built and my stick/peddles not installed yet I am just starting quick missions and putting the plane in autopilot to gauge performance. With these settings even the london mission is smooth.
I suppose I shouldn't be surprised....but somehow I am