Please help me understand which config for a Z1190

I am going to buy a new laptop. I am pretty set on the Z series, and leaning towards the VCP Z1190 CTO from the Sony Outlet, as there does not seem to be much difference between the 1190, 1290 and the 1390, and I am fine with a resolution of 1600 x 900.
I use the typical MS Office.. nothing heavy duty, iTunes to watch movies when traveling. ... web surfing...etc

I am into photography, and will be running Adobe Lightroom 3.2 and Photoshop. I only use my laptop for simple editing, (but with RAW files).
I *think* the difference between the i5 540 (at 2.53Ghz) vs the i7 620 (at 2.66Ghz) will provide an almost unnoticeable difference. I am wondering if I will see any performance gains between 4, 6 or 8GB of RAM. I see there are many units which say 4GB x 1, which I figure would be easy to upgrade by adding a second stick of 4GB (instead of systems coming with 2GB x 2). I am also concerned about the systems which have 6GB (1x4GB, and 1x2GB) as I have read that Windows 7 64bit is more efficient utilizing dual channel (doesn't that mean you need two sticks the same?)

Any help you can give would be greatly appreciated.

Thx

 

Correct.

You are pretty much right. There won't be much noticeable difference.

I think you should be good with any of 4 GB, 6 GB or 8 GB, if you are not a heavy multitasker. If you are, then go for 6 or 8.

I'm not sure if 4GB+2GB would be slower than 4GB or 2GB+2GB RAM setups.

 

the difference will be very small and only noticeable in benchmarks (probably)

 

Guys that you for the responses.. It sounds like the one I found for $1599 will is a good deal (I just have to add a longer warranty);

# Display : C50876001
# Color : Premium Carbon Fiber
# Wireless Wide Area Network : No Mobile Broadband Built-In (this will remove GPS functionality)
# Processor : Intel® Core™ i5-540M processor (2.53GHz) with Turbo Boost up to 3.06GHz
# Hard Drive : 128GB (128GBx1) Solid State Drive with RAID 0 Technology
# Optical Disc Drive : CD/DVD Burner
# Battery : Standard Capacity Battery
# Channel : C50876059
# Warranty : C50876063
# Operating System : Genuine Windows® 7 Professional 64-bit
# Software Optimization : Fresh Start
# Software : No additional Office Software
# Software2 : C50876091
# Photo Software : No additional Photo Editing Software
# Video Software : No additional Video Editing Software
# AntiVirus Software : No additional AntiVirus Software
# Base Unit : C50876431
# Battery Color : C50876492
# Memory : 4GB (4GBx1) DDR3-SDRAM-1066
# Limited Warranty Term : 90 Day Limited Warranty

 

If they have a version with a larger drive, 192G, or 256G, that may be worth looking into.