I7 very fast. When you get more memory to make better use of the CPU, you'll likely find that 8 GB is enough. When doing batch processing of many files I have monitored the CPU and RAM usage. The processor reaches capacity before the memory does. Don't forget to adust settings to allow CS5 and LR to use more of it. If motherboard is capable, a higher RAM access speed will benefit you when doing batch processing.

Is it possible to squeeze one of the flash hard drives into it as a second hard drive? If so, you may want to consider using one if you do batch process raw/jpeg/tiff conversions or if you do much work with video. The improved read/write times really improve the speed when doing files big enough to require spooling on and off the hard drive. Had one put onto my machine at work as I do a lot of video work and it does make a difference.