need help removing this virus

my computer has this really shitty virus. the virus is basically pretending to be a software program telling me that my computer is infected with a virus. it annoyingly pops up constantly telling me that my computer is infected with this virus. after a while, the look of my desktop reverts back to an older style of windows. how do i get rid of this?

if i get an external hard drive and put my music, pictures, and word documents onto the external from the infected computer, then transfre everything onto a new computer, will the virus infect the external, and possible the new computer?

Download OTL by OldTimer to your Desktop.

• Close all windows and double click OTL.exe
  
• Click Run Scan and let the program run uninterrupted
  
• It will produce two logs for you, one will pop up - OTL.txt, the other will be saved on your Desktop - Extras.txt. Post both logs in this thread.
  
• You may need to use two posts to get it all.
  

what is this for?

So we can scan the machine and find the malware.