It is very unusual for a spyware program program to suggest that a site is endangering your machine & then allow you onto the web page. Rather defeats the object of it...
This is what PCWorld say about PC Tools free anti-virus when they tested it...
Bottom Line
PC Tools Antivirus, which neglects to detect spyware, allows far too many pieces of malware through for it to realistically protect any PC.
AGV or avast! might be a more reliable choice if you are looking for a free checker for Windows XP/Vista.
Microsoft Security Essentials plus something like Malwarebytes if you are Windows 7 is probably as good as anything.