Some brand new Viliv S5 MIDs have been found to have viruses infecting them, despite being fresh from the factory. Nobody knows quite how many of the 4.8-inch touchscreen mini-tablets are affected, but there have been multiple reports that those machines have several viruses present.
Anecdotal research suggests that it is the English-language build of Windows XP Home that Viliv have used on some models that is tainted. The install is a custom mixture of the Microsoft OS and Viliv's own modifications, which offer things such as an on-screen keyboard.
The viruses in question include kinza.exe, win32.QQrob-32 and ActMon-Pro. Current advice is to run a virus scan as soon as possible if you pick up an S5, preferably before connecting it to your home network or attempting to synchronize data between it and an existing system.