I had some problems with this as well. I was on win 8.
- Install the SDK and USB driver from Google. USB driver is available in 'Android SDK Manager' in eclipse.
- Put the tablet in developer mode by clicking on 'About tablet' and clicking the build number seven times (crazy)
- Open Windows Device Manager and right click 'Android ADB Interface'
- Click Properties
- Driver Tab
- Update Driver
- Select 'Browse my computer for driver software' Select the 'sdk' folder under the location you installed your sdk in step 1 (e.g. D:\Dev\Software\adt-bundle-windows-x86_64-20130219\sdk)
Not sure why windows didn't auto-detect it but it didn't. Could have been because google doesn't actually 'install' the driver into windows or perhaps it was because I had the HTC USB drivers installed because of my old phone.