The sites you mentioned appear to be designed to scare you into downloading and/or purchasing software that may or may not have benefit to you, or worse... Neither one is an official Microsoft patch download site.

You should never click on a link or visit a website that purports to offer security patches, unless you are 100% sure that you are accessing the official WindowsUpdate site. Click on Tools -> WindowsUpdate in Internet Explorer to access Windows Update. Follow the instructions there for receiving automatic updates, and you'll never need to visit the site again.

The messages you mentioned could be harmless web browser popups that you can close and ignore. The Google Toolbar can help to block most popups. Another possibility is spyware or a virus on your PC.

I suggest you do an immediate spyware scan, then make sure you have up-to-date virus protection in place. The article Spy, Counter-Spy will tell you where to find the anti-spyware and anti-virus programs I recommend.