I went to a site (don't want to post link because it might be a dangerous website), and although I'm not sure, I feel that it may be a website that tries to install something malicious onto your computer. Does anyone here know enough about what type of protection no-script gives, and if it would be enough to protect me from anything the website would have tried to install onto my computer? I tried installing MSE (saw people talking about it from this forum), and it said that it didn't find any threats. If I had become infected with a virus or keylogger, would it have been found out?
Run malwarebytes in safe mode with networking to check for malware.
NoScript is a pretty good add-on. It disables all background scripts from running, unless you allow them. I actually found it to be a pain, because it blocks SO much from running. Rest assured, it'll keep malicious scripts from running.
Having a good antivirus software (Avast, Microsoft Security Essentials, or Avira) installed and running is very important. That software can run in conjunction with NoScript, as NoScript isn't a stand alone antivirus software.
I won't go so far as to say that NoScript will prevent all malicious web pages from harming you - but it will certainly stop a lot of them. It doesn't just disable scripts, it also disables flash, pdf, clickjacking, cross-site scripting, and a slew of other infiltration routes.
I like it because it uses a "whitelist" approach - don't allow any sites unless I say it's safe. I also like it because it's very easy to add sites to the whitelist without having to burrow down into tools / options / security / etc. settings.
NoScript's unique whitelist based pre-emptive script blocking approach prevents exploitation of security vulnerabilities with no loss of functionality.