You can restrict certain web sites to install software on your PC.
This one works for Internet Explorer.Follow the steps below.
Navigate along:


- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
\CurrentVersion\InternetSettings\ZoneMaps\Domains

Create under Domains a new subkey named like the top domainname
of the web site you want to restrict.example:www.name of web site.com

In the right pane of this key create a new REG_DWORD [Dword Value]
and name it "*"(without the marks).
Doubleclick it and set it's value to 4 (restricted)


Restart Internet Explorer!



Note:Using this tweak does not replace a Firewall.