Just double-click on the executable (currently 'stinger32.exe') in your download folder. If you wish it stay current, you will need to download the latest version frequently.
It claims to update its virus list several times per week, but there is no way to update this via the GUI. On my XP and Win7 systems, it did not conflict with either avast! Free or MSE resident AVs. It provides no real-time AV protection, and is not a replacement for your regular resident AV. However, it can be configured to 'Report' or to 'Remove' instead. By default, Stinger will repair all infected files detected.
It works on Windows XP, Vista, and Win7 operating systems, both 32 and 64 bit. Stinger is a free standalone on-demand utility that both detects and can remove specific viruses, trojans and variants (currently over 6200 in its list).