I wouldn't use a USB stick to transfer it; god only knows what malware is waiting to jump onto removable media...
I've uploaded the latest MalwareBytes (1.46) installer to my webspace for you, renamed to a random collection of letters and numbers. That usually helps it get past any malware looking out to disable known anti-malware tools. You can download it
here.
* Disable system restore and delete all restore points
* Run MalwareBytes in NORMAL Windows mode (not safe mode), update, then full scan
* Reboot
* Run something like Dr Web (in Secure Desktop mode), SuperAntiSpyware etc
* Reboot, run MalwareBytes/SuperAntiSpyware/Dr Web in safe mode
* Personally I like to run an online scanner (eg BitDefender, NOD32) now + ComboFix
* ???
* Profit! (hopefully)
Good luck.

As you say though, depending on the machine and its content, it might be easier (and provide more peace of mind long-term) to just hose the hdd and start again.