The 4-in-1 drivers are a necessity for boards with a VIA chipset (in your case, the south bridge, in mine the north bridge as well), so that may have something to do with it. Did you reinstall Windows when you installed the MB? Or did you use another method? If you just changed MB's and then booted up and let Windows redetect everything, that's a bad sign. Windows *always* has to be reinstalled when you change motherboards, and from my understanding the order of installation is Windows-> 4-in-1 drivers-> service packs (if it's Win2K). If you have junk in your system from your previous MB, then that might be causing part of the problem. I pulled my SB Live and tried to install my Santa Cruz, but the drivers refused to install because there was still Creative stuff left over in the system, and I couldn't get it in until I did a clean format and install (which I was doing anyway because I changed MB).
Also, have you installed any patches for Giants? There may be a fix for your issue in the latest patch if it's not installed already.