As a general rule of thumb, you should never download freeware apps unless it comes from a reputable source. Otherwise you could be letting yourself in for a whole lot of trouble if that cool little freeware app happens to contain malicious code. However if you MUST try out a new program which has come from dubious sources, you can use a Windows feature to protect your PC.
When you have downloaded the program, don’t double-click to install it just yet. First, right-click on the program icon and choose “run as”. When the “run as” box comes up, you’ll see the following box :
Select “current user” and make sure the “protect my computer and data from unauthorized program activity” box is ticked. Then click OK. You can then do a limited installation of the program in “safe mode” so you can check it out. Having the “protect my computer” option ticked means that the Registry can be read by the application but the application can’t change anything in the Registry. So if there is any rogue code in that freeware app, it won’t wreak any havoc on your PC.
When you are convinced that the app is OK, come out of the safe mode and install the program properly.