This is under the presumption that the PC can boot into Windows...or at least into safe mode.
I have a USB drive and I download the install files of the following onto it from a clean PC:
Either IObit Uninstaller or REVOuninstaller
Windows Repair (All in One)
The majority of these can be found for download on CNET or Bleepingcomputer.
The Windows Repair Tool is at tweaking.com.
If I can make it into Windows on the infected PC, I insert the USB drive. I then drag and drop the programs from the USB drive onto the desktop.
First I run rkill.
Rkill runs a scan and tries to stop (not remove) any malicious processes it may find.
Then I update and run TDSSKiller.
After it gets through, I install and run SuperAntiSpyware and Malwarebytes...full scans.
If there is any anti-virus program, I stop any active protection in order to run Combofix.
After Combofix, I install and run an uninstaller (IOBit, etc) program to find and completely remove junk and unwanted programs.
After this, I install and update AVAST free, and then I run a PRE-BOOT scan.
The final step I normally use is running the Windows All in One Repair Tool. It takes you step by step through a process (including check disk and system file check) and a final process that corrects and restores Windows settings.
Depending on the existing anti-virus on the machine, I may or may not uninstall AVAST.