On the decision for the cooler, the stock cooler with do you for now until you do overclock. Unless you can afford an extra £30 for the Gelid Tranquillo! Excellent cooler and will cool that i7 overclocked to hell!
If you do change your motherboard, for an extra £15 get the Asrock Z68 Extreme 4 Gen 3:
http://www.overclockers.co.uk/showproduct.php?prodid=MB-051-AK&groupid=701&catid=5&subcat=1990
This board is a lot better than the MSI board you have at the moment. Read up on it in last months PC Format/Custom PC. Cannot remember which lol, but was in one of them, and it got great results. Far better than the MSI board you have at the moment.
If you take out the i7 for the i5 you will lose hyper-threading technology which is in the i7 only and not the i5, which battlefield 3 will use a lot of! If you want to get the best of out battlefield 3, keep the i7.
But if you take away the 570 for the 580, then you will get slightly getter framerates, and i mean an extra 10-15fps. Is it worth sacrificing the hyper threading of the i7 for and extra 10fps, but think about it, with hyper threading, you should be able to get them 10FPS back with the 570 as you have a faster cpu.
Stick with what you have and your good to go! i7 + 570 is a nice combination and will play battlefield 3 on high settings @ 1920*1080 very easily with AA on max. You should easily get around 60fps+ and I mean easily. When you get the rig, download the beta version of the game, or at least try bad company 2 on the highest settings, should give you a LITTLE feel on what it may react like!
And thanks for the "saying thank you" for the advice I have given you. Could you at least, click on "trust" in this post, so I can get some nice rep.
Thanks Dude
Anything else, either ask me here, or go to my profile and email me.
Enjoy the rig!