Hehe, I agree, your computer hates you.
That's kinda strange, maybe your sound card is dead but I doubt it.
Did you canceled the installation when Windows found a new driver? Because you should totally ignore this and finish the installation and reboot your computer without choosing a driver or following Microsoft's instructions.
If that's what you did, you can, as you said, install the driver yourself, by right-clicking on "PCI Multimedia Audio Device" in the device manager and select "properties", then "driver" then "update driver". You can then "locate the driver yourself" and select the file "SIS70120.INF" located in one of the folders of the zipped file. The folder must be your OS (you must have Windows XP right?) so it would be: "a12112b\WinXP\SIS70120.INF", maybe it will ask you for the .cat and the .sys also. But maybe you already did that when you said " I 'manually search for a better driver', and it won't find them itself. " is that so?
By the way, is your sound card built-in (directly on the mainboard, as SiS calls it, instead of a motherboard hehe)
or is it a PCI card? because sometimes, you need to anable the sound driver in the BIOS when it's built-in.
If the problem still persists, I would gladly give you a SoundBlaster Live card that I don't use, but I live in Montreal