You can remove obsolete Service Pack files with DISM.EXE:

or use this cmd file.

DISM /online /Remove-Package /PackageName:Microsoft-Windows-Foundation-Package~31bf3856ad364e35~x86~~6.1.7601.17514  

In time your HDD will be filled with logfiles, dump files, and other temporary files. Since Windows XP there is cleanmgr.exe. This one pops up if your HDD gets low on diskspace. But we don't want the default actions as compressing files etc.

To take things in your own hands there are more powerful options in cleanmgr.exe than meets the eye. 

Setup cleanmgr.exe as follows:

Now select what you want it to clean up. It will be saved as set 1. Now we want cleanmgr to actually clean it. For that use:

Remove Packages

Also you might have noticed the ridiculous growth in the c:\windows\winsxs folder. This folder holds packages/dll/mui/setup/sp etc. files for Windows 7 OS. 

 

Also you might find foreign language files you don't need:

And you can remove then with:

You can make a cmd file to get rid of them. An example can be found on my script page: RemovePackages.cmd.

reset winsock:     netsh winsock reset

reset ip/dhcp:      netsh int ip reset

reset tcp params: netsh int tcp reset

One advantage is that you have more space in the explorer window to right click. You can enable it by running the DisableFullRowSelect.reg file. Instructions are in the reg file.

 

Beside that I find it very convenient to add some commands to the CMD bar of explorer. These commands are folder type specific. By disabling FullRowSelect we have reset to the Generic folder.

Now we can customize the CMD bar with the expl_cmdbar.reg file. You need to take ownership and full permissions of the registry key used in the file first.type. All possible command can be found in the registry at: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\CommandStore\shell

Since Windows 95 we have PnP. Plugin in some hardware and the PnP system finds the driver in c:\windows\inf or from your local media, later even from Windows Update. The major flaw with this system up to today is that if hardware is removed it never asks the question "Should I remove the driver now too?". So after a few years you system is cluttered with old device drivers. This slows down your system a fraction. No real big deal but lets do some good housekeeping.

Now start the Device Manager and select from the View menu Show hidden devices.

Goto the top of the tree and press "*" on you numeric keypad. The tree unfolds. Now look for greyed devices. They are not on your system. Press delete. Don't do this for the "Sound, Video and Game controllers" or there must be some old sound board present.

In general you can do this for mouse(hid), keyboards, disks and disk controllers, usb, network, modems, etc.

In PnP language the main groups (e.g. Network Adapters) are classes with a corresponding ClassGUID. The Network Adapter Class has a GUID of  {4D36E972-E325-11CE-BFC1-08002BE10318}

From point 6 it is different for every device class.

ps: the inf folder is pointed at by HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion DevicePath. You can use ; to point to multiple paths. In older versions of Windows it was possible to trigger a new PnP Device enumeration process with RunDll32.exe SysSetup.dll,UpdatePnpDeviceDrivers but the new SysSetup.dll doesn't provide that anymore.