Wait... You said you reformatted.
1.Did you copy any previous files or backup any files to put on your computer after the format? They could contain infected files that the Trojans/other have tampered with.
2. Are you sure you reformatted? Because if they came back after 1 night it sounds as if you did something else, because if they where on your computer, they wouldn't stay dormant for 1 night and then reactivate.
3. I highly doubt that uTorrent is "causing" the virus, when i say causing i mean its using uTorrent as a activation to bring the virus back into your system, (THOUGHT* they could be download through there if you are not careful of what you are downloading)
Finally, make sure you go though Osiris's guide like he said, and maybe disable your internet connection after downloading all the programs and then run them.