ok then you can try some of my old tweaks, the latest is made to work best with SP2
download this attached file (Cable & DSL 3000 256.zip ), unzip it to C:ProgramCablenut
open cablenut adjuster, click delete cablenut tweaks and click save to registry, in top left corner click file, load custom settings file, browse to C:ProgramCablenut and dubble click on the file you unzipped.
now click save to registry and reboot
check speed again, use the 2992 KB testfile for download and 1496KB testfile upstream, also make a new tweaktest and post result
good luck
VanBuren