The only problem with this test is, that flight sims are not like most games. There is a lot of computing going on.

Can anyone comment on results running a Radeon HD 7750 1 MB card for CloD?

SAPPHIRE Ultimate Radeon HD 7750 1GB 128-bit GDDR5 PCI Express 3.0 x16 HDCP Ready Video Card

My GTX 460 just expired and I need to replace it.

I don't want to spend very much money at this time, and like this one because it is fanless (and therefore silent) as well as cheap and has low power requirements.

In less then a year I will build a new system and maybe splurge on a GTX 670, but until then I would like a stopgap. Expectations will be only for medium type settings and performance.

7750 is inferiour to your gtx460 by a good margin (http://www.anandtech.com/bench/Product/614?vs=542) , so dont do it. Save up and get the 7850 which is about £150 (if you shop around) and will get you about x2 460 performance when OCed. Or maybe 560ti - if you can find one significantly cheaper than the 7850. Anything less is not worth it for CLOD imo.

DO NOT drop it off at best buy.....DO NOT!!! putting in a new video card is slightly more involved than putting in ram, both are easy...and may start you on the road to computer competence and soon you will be building your own system as you learn....

And try for a card with more than 1 GB Video ram.

Better say try a card with more than 2gb! :) 1.5 perhaps won't make you happy.

Concerning 2.5k or even other cpu: If a cpu is too slow, it bottlenecks, but a 2500 k doesn't need to be running on 4,2ghz as it perhaps gains 1 or 2 more fps in clod in comparison to tweaking it to 3.3 or up to 3.7. From then on, the cpu should not bottleneck and mor cpu power do not gain much more fps. To gain fps and performance, better buy a video card with more than just 1 gb. I would say, that 2gb is minimum in my point of view!
all additional stuff helps you stabilizing like better ram or an ssd drive, as streaming engines are performing better, when u use ssd. Even your general experience of your whole pc will invrease.