|"Microsoft Security Essentials" and "Virgin Media" both run in the background. You should only have one doing this but you are probably OK to use the other one as an extra scan when you want to use it (like a second opinion).|
I don't know how good the virgin media one is, but Microsoft Security Essentials gets fairly good press. On that basis I would keep them both installed but turn off the real time scanning in Virgin Media if you can. A website suggested that you uncheck the box enabling Anti Malware in the Anti Malware section of the user interface.
Always pop back and let us know the outcome - thanks