As I tried to avoid explaining in my slightly facetious previous post your chums chum is actually correct in a sort of way.
See
http://www.arstechnica.com/paedia/r/...e.part3-1.html
"On an added note, this discussion illustrates why two, 512MB DIMMs of SDRAM will outperform a single, 1GB DIMM. Since each DIMM can have up to four banks, regardless of its size, spreading your memory out among multiple DIMMs offers better performance because of the increased number of banks."
Presumably this is what he may have heard. Just remember that there is NO guarantee that 4x32MB will be faster than 1x128MB - it depends also upon the memory architecture of the mobo and how the designers have chosen to implement this (as well as the RAM speeds and quite a bit of other stuff).
If ya realy really want to get involved in RAS, CAS, tRAC. tCAC, cycle times, dualocts and all the rest of it then Jon "Hannibal" Stokes has an excellent and readable (but necessarily long) tutorial starting at
http://www.arstechnica.com/paedia/r/...e.part1-2.html
If you slog carefully through it all and make notes then you'll know more than I do
