It is ICO_MYCOMPUTER.ico in explorer.exe in the Icon folder in C:\Windows
You will need a resource hacker of some kind so you can open the explorer.exe and import a new icon in its place. I would recommend getting a copy of explorer.exe and putting it on your desktop and then edit it leaving the original untouched until you rename it using the steps below.
Then you'll want to change the explorer.exe do the following.
To properly change a system file you need to take ownership give yourself permission and rename the old file and then copy in the new one look at Post #6 of this thread will tell you how to do it http://www.sevenforums.com/customization/179502-basic-networking-information.html#post1525656
Let me know if you need any more help.
Jerry
My Computer
At a glance
Win 7 Pro x64 / Win 10 ProIntel(R) Core(TM) i7-3630QM CPU @ 2.40GHz12 GB(1) Intel(R) HD Graphics 4000 (2) NVIDIA GeFo...
Computer type
Laptop
Computer Manufacturer/Model Number
Sager NP9170
OS
Win 7 Pro x64 / Win 10 Pro
CPU
Intel(R) Core(TM) i7-3630QM CPU @ 2.40GHz
Motherboard
CLEVO P170EM
Memory
12 GB
Graphics Card(s)
(1) Intel(R) HD Graphics 4000 (2) NVIDIA GeForce GTX 675M
Sound Card
(1) Realtek High Definition Audio (2) Intel(R) Display Aud
Monitor(s) Displays
17.3
Screen Resolution
1920x1080
Hard Drives
(1) Samsung 860 EVO 500GB(OS) (1) Samsung 860 EVO 500GB(Data)
Keyboard
Backlite
Antivirus
MSE, Malwarebytes Pro
Browser
Firefox
Other Info
DESKTOP: Custom-built.
OS: Win 10 Pro x64.
CASE: Rosewill R5.
CPU: Intel I5 4670K CPU @ 3.40GHz.
CPU COOLER: Cool Master Hyper 212 EVO.
MOTHERBOARD: Asus Z87-A.
MEMORY: Kingston HyperX 2x4 GB.
GPU: Nvidia Geforce 650 TI.
PSU: Corsair TX750.
DRIVES: (1) Samsung 840 120 GB SSD (2) Western Digital blue 500 GB 7200 RPM.