Installed the drivers
for the wireless card from Belkin? Whether it will help or not here is a copy of the nwifi.sys from my System32 folder, nwifi.zip
May have to boot to safe mode to replace the original (good idea to rename the original to something like nwifi.old before adding the new one).
OK, so no extra controller card. Which of the SATA ports do you have your SATA drive attached too (group 1 or group 2)?
If it is #2, I would connect it to #1 and disable the "Onboard GSATA-II Ctrl" in the bios. And if nothing is connected to either of the GSATA ports, again disable it.