I currently have 2*1GB. I can get a single 4GB kit for the same price as 2*2GB. I understand that using 4+1 would disable dual-channeling, but that's still 25% extra capacity. Would it make that much of a difference? Normally I have Safari, Adium, iTunes, Pages, TextMate, Preview, Springy and jDownloader running. I do occasionally iMovie and PS CS5. So, any idea which set up is better for my needs?