What is pw.exe? Should I remove it?

pw.exe is an executable file which primary purpose is to start a parasite or launch some of its components. Once executed, the pw.exe file runs a process that is responsible for the parasite's payload. pw.exe is a significant part of a dangerous threat, but it can also work on its own. DO NOT execute it!
The pw.exe file is installed and used by Vista Security 2011.
The pw.exe file usually runs the same named process. This process silently works in background and performs harmful actions. It remains active while pw.exe is present in the system. Removing the file will immediately terminate a process and prevent it from running later. That is why you have to manually delete the pw.exe file. If you cannot erase it, consider using recommended spyware removers, which will get rid of pw.exe and associated parasites for you.
Please note that the pw.exe file actually may be a fully legitimate part of the operating system or legitimate software. Often parasites use files with unsuspicious names, but malicious functionality. You should always carefully check the file before deleting it. It may not be related with malware, but can be required by your essential programs to work properly.