Long story short, I ended up with the above mix of RAMs. I have a Win7SP1 32 bit machine with 4 RAM sockets max 8GB. I am not sure which mix of RAMs is better overall for normal use with some non-demanding games (steam). I know the 3x1GB mix will not run dual channel unlike the 4x1GB mix.
However, will 4GB dual channel symmetric at 266Mhz triumph over 3GB dual channel asymmetric at 667Hhz?