Windows 7 icons are different from windows vista. Most of the all windows icons are stored within system32 dll files which you can extract with resource hacker like tool.Taimir asad from randompie has done the job of extracting windows 7 icons from various .DLL files in /Windows/System32 and has shared with us.
This Windows 7 beta icon pack contains 214 Hi-Resolution icons which are in original ico format. Please keep in mind that these icons are under Microsoft copyright. You need to be careful while using these icons.