GoogleUpdate.exe is a legitimate process, which is installed on computer in a bundle with Google products. It can be embedded with Google Chrome browser, Google Picasa, Google Earth and other programs that belong to this company. Just like its name suggests, this process is responsible for keeping Google products up to date, so you shouldn't terminate it if you want to avoid issues with previously mentioned programs.
As soon as user installs GoogleUpdate.exe, it starts running automatically in the background: it looks Google servers for newly released updates and downloads them. However, this process initiates various problems for its users when they try to disable it. Beware that after ending this process, it automatically comes back when Google Chrome is launched for the next time.
Scammers have started hiding their viruses with a help of legitimate files' names! GoogleUpdate.exe may also be involved into this, so you should be very careful with that. If you noticed this exe file and you don't know where it came from, you should check this file with a help of RegCure Pro.