If you’ve already downloaded Firefox 3.5, then you need to make an urgent update.

Firefox 3.5 is less than a month old and 3.5.1 is already out to fix a critical security problem with the new JavaScript engine.  The flaw with the new TraceMonkey engine made it possible for malicious coders to run arbitrary code through JavaScript and inject malware into your system.  The 3.5.1 update patches the hole and is considered a critical update.

To update do the following:

1. Click on “Help” in the upper toolbar.
2. Click on “Check For Updates”.
3. Follow the prompts.

In some cases your system will download the update automatically and then prompt you to run the patch.

Again, this is a critical update and you should not waste any time in doing it.  It doesn’t take much time and will make your web browsing that much safer.