What security software did you install ?
You are sharing a router which will block a variety of incoming hack attempts. If you have anti-virus software on your machine (and allow it to scan daily or weekly, as well as scan anything you plug in such as memory sticks, or whatever you download, and your incoming e-mail) then your security is still going to be adequate for most purposes.
If others use your PC, then you may want to ensure they cannot install software (indeed, assuming you have an administrator account and a 'user' account then logging in to browse, etc on the 'user' account means that most software which might be downloaded (eg a virus) should not install.
However, some software (such as MS Internet Explorer) is more prone to attack (there are BHOs [Browser Helper Objects] which have been identified as significant targets for hackers to use. A BHO gets automatically loaded with MS IE whenever you use the browser (and therefore cannot be deleted while the browser is in use). So security depends on a number of factors, including how often you scan for malware, what you [or others] do when online, and how susceptible people are to clicking on random links sent by e-mail or within instant messager services.
The son of one of my clients clicked a link claiming to be an "Angeline Jolie" screen saver but was a nasty virus which prevented many attempts to destroy it, so security is difficult at best, and horrific at worst, if people do not act with a degree of care when online.
If your security software blocks use of the internet, then you need to either find out how you can control that software, or it is being excessively over protective !