I'll see if I can find any more info that might be useful ...
When present, there is always also another file by the name of "secret.exe" which makes people nervous as it could be exploited by hackers. Let me quote from pedantic Microsoft: "matcli.exe is a motive Assistant Command line interface that gathers information about your system's identity like your name, e-mail address, city, state, etc. and gets written to a log file while silent.exe executes matcli.exe quietly in the background." This file was introduced when HP bought Compaq. It is required to run some of the special data provided in the Compaq Knowledge Center.
These files were introduced when people bought a new HP printer. You did not say if you also have a Compaq computer. In that case, if you were to remove these files, you might no longer have access to items such as "Fix my Presario computer" wizards. I will leave that decision up to you. The standard way to remove this program is by going to Start | Settings | Control Panel | Add or Remove Programs | Select HP Instant Support | Change or Remove Programs | OK. If later you feel naked without that support function, you can reinstall it from the printer driver diskette.