Maybe the best is to go with Windows XP. I wonder though, if you could find out, what kind of audio chip is that, maybe you could find something to try out.
For example, I started looking around on the lenovo site, and some computers of that kind had audio driver for "SoundMax Integrated Digital Audio". Now, if I search that with "Windows 7", there are some interesting results... No idea, how useful, but interesting, anyways. Good luck!