Most of the configuration like changing upload frequency is done in the registry. The registry keys for the gateway are stored in HKEY_LOCAL_MACHINE\Software\Microsoft\SystemCenterAdvisor\Gateway and the registry keys for the agent are stored in HKLM
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Read the complete post at http://scug.be/blogs/scom/archive/2011/05/09/system-center-advisor-changing-the-upload-frequency.aspx