saimah,
The short answer is 'No' as any decent IT person, if we have physical access to your system, with the available tools we will be able to get logged on in time. You've asked a question that not everyone will answer with the same response. Security is a balance between usability and risk and needs to be done in layers. I would suggest that you grab a few IT Security related books as well as look at several websites like:
http://www.microsoft.com/security/http://www.windowsecurity.com/http://securitypark.bitpipe.com/http://www.sans.org/reading_room/Security Training
http://sans.org/http://www.sans.org/security-training.phphttp://www.isc2.org/There's a ton of stuff out there, and a lot won't be applicable to your environment. The above links are just a very short example list and there are a whole lot more available.