Correct win 7 & win 8 act funky when it comes to the drivers, here are the steps for win 7 & win 8. I've done the install on win 8 for several of our customers to date.
Windows 7, 8 , Vista & XP 64 bit operating systems driver install instructions
1)Download the drivers here
http://www.hptuners.com/pub/HPT FTDI...08.28 WHQL.zip
2)Unzip the drivers to your desktop
3)Connect your MPVI interface to your laptop
4)At this point the driver install will likely fail(it did for me)
5)Open the control panel and in the search window enter device drivers
6)Under Device manager select the update device drivers one
7)There will likely be two MPVI devices with an ! listed next to them in the 'other devices' section
8)Right click on the first one, click update driver software
9)A window will come up, tell it to browse my computer for driver software-from there find your desktop
10) it will now install properly
11)repeat for the second one and you're done!