Upgrade laptop and netbook memory

I just got a combo HP laptop and HP netbook, and I'm looking to upgrade the memory (to maximum) in both. The laptop is the G60, and came with 3 GB of RAM; the netbook is the 8.9" screen mini, and came with 1 GB of RAM. The G60 will remain a 32 bit operating system, so is it even worth upgrading to 4 GB if it's only going to see/use 3.2 of it? Will having 2 x 2GB sticks allow it to run in dual channel mode?

My idea was to buy a new 2 x 2GB kit for the G60, and use the 2GB stick I take out for the netbook. This will leave me with two "leftover" 1GB sticks in case any of the memory ever goes bad in the future. Any suggestions on what I need to get? Will I see much of a difference between CAS 4 and 5?

Thanks for any/all help, and I'd be happy to provide any further information if you need it.