so guys, I've decided to get some more ram for my system, as I think it's either the ram or my cpu that is causing lagging problems whilst playing bf3 and on teamspeak, so since ram is the cheaper option, I'm gonna try that first 
so I need a little help, should I get 4gb more dominator ram to run with my current ram, or should I get an 8gb kit of something else like the 8gb vengeance blue kits?
there is only one problem for going for the 8gb option, I only have £42 to spend iirc, and the 8gb kit that I like the most is on a competitor's site for £46
but what are your opinions guys?

so I need a little help, should I get 4gb more dominator ram to run with my current ram, or should I get an 8gb kit of something else like the 8gb vengeance blue kits?
there is only one problem for going for the 8gb option, I only have £42 to spend iirc, and the 8gb kit that I like the most is on a competitor's site for £46
