When I moved my T60 laptop from XP to Win 7, I noticed a huge improvement in sound quality. I was using Foobar2000 on both operating systems, but just kernel streaming (ASIO4ALL was too buggy for me) in XP and WASAPI in Windows 7. I confirmed with an external box that XP was re-sampling everything to 48kHz, and Windows 7 with WASAPI keeps the native file sample rates for output. Listening was all through a headroom ultra desktop amp whose DAC was fed S/PDIF from the laptop dock. It has an ASRC but is still sensitive to jitter, which is probably also better with WASAPI, in addition to the lack of re-sampling.