Someone hacking my bro's computer

Hi guys,

I need your urgent help. I have fixed my brother's computer by reinstall windows 7. Everything is working fine especially the local area network connection issue, but I can see that something is look very suspicious. When I opened on 'my computer', I can see that somebody called 'ALEX-87D3DC2A24', is connecting to my brother's computer few mins after when I enabled the nforce network controller. I am really scary that if he will be hacking him to break into his computer and steal the information.

Here is the screenshot:




Does anyone know what I need to do to to prevent him hacking and prevent him break into my brother's computer?


Any advice would be much appreicated.

Thanks in advance