To anybody still trying to still accomplish this i found an easier way then the hassling replacing system files manually way and it works like a charm!
Step 1: Download this software - CustoPack Tools : Customize Windows XP, Vista, 7
Step 2: Open software and click "Create a CustoPack" and then "Create a new Pack" in the bottom right corner and fill out any info and check "Windows 7"
Step 3: Goto "Standard Icons/Folders" and change the top 5 icons to your custom ones.
Step 4: Goto "Pack Finalization" on the left menu and click "Test the Pack"
After applying they should be working fine.. This worked 100% for me if it doesnt there is also a "Purge Icon Cache" under the main menu "Settings and Configurations/System Configurations"