network control

Can anyone sitting on a local area network control the other PC and read already opened files on that PC., lets say it like that, Can i stop or play a song running on another PC which is on my network?

Yes. There are software available that are capable of doing those features that you are saying. The name of the software is Remote Admin. Edited to remove Signature Advertisement. Doug

With XP, Microsoft calls it Remote Desktop
http://www.microsoft.com/windowsxp/using/m…ty/default.mspx

MS offers other utilities for remote "Computer Management"
http://support.microsoft.com/kb/308423

There are other third-party free and paid products to do the same, with various advantages to each based on what type of remote management they offer.

I use Logmein - free version.

Thanks i understand it now.. though i can not name the software here