not a clue how to stop a program accessing the web so can someone help me out with this please. thank you
Presumably you aren't using the server version of avast since you aren't using a server OS, so this should have gone in the avast 4 Home/Pro forum.
avast isn't a firewall so it can't do that - Firewalls are what you use to block access to the internet, so what firewall are you using ?
Does win7 not have a firewall like Vista, if so that would probably have outbound protection (probably not very user friendly), but probably like Vista outbound protection is disabled by default.
This is compatible with Vista 64bit, so at least it is compatible with 64bit OS, but I don't know if that would stretch to win7. Outpost Firewall 2009 free, a cut down version of the Outpost Firewall Pro version, which should still provide good protection, see http://free.agnitum.com/
. Download, http://www.filehippo.com/download_outpost_firewall/