Acer Aspire 5515 Windows XP downgrade. Need driver help?

Picked the $348 Acer Aspire 5515 up at Wally World last week and I am trying to downgrade from Vista to Windows XP. After installing XP I had five device drivers. I have found the audio, video, LAN and WiFI drivers but I am still in need of the SM Bus Controller Driver. Anyone have any ideas? Thanks in advance!!!
Update: P.S. Already tried the Asus web site but they only list drivers for Vista and they are not even available for download.
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