Shouldn't have any problems. Drivers for Win7 are compatible with Win8, so it should be smooth sailing.
I was serious about returning it.
Actually, WUGS is how I got Nexus 7, Galaxy Nexus, drivers on my Windows 7 laptop. It's not a problem you can blame on Windows 8.I read the other day that if you want to pi$$ off someone, give them Windows 8.
You can take relief in the fact that as long as you don't alter the bootloader partition and you can get into fastboot mode, you should be able to recover the tab from just about any mess. Just be aware that unlocking the bootloader will wipe the device clean. After that you are able to get into the wonderful world of custom roms, kernels, and much more.
On Windows 8 I usually have to go to pc settings/general/advanced startup and restart with the option to allow unsigned drivers in order to install the drivers for my various Android devices. I'm not sure if the drivers you need for the Nexus 7 are signed or not...I just enabled the unsigned drivers before I tried to install them. The option does not persist after rebooting so you need to restart in the advanced mode each time you want to install new drivers.