As far as I could check it the Router?s Hardware Firewall is doing very good job controlling incoming junk.
However, it seems that they do not control the outgoing info (Adwares, and foistwares that call home).
Recently I came across shareware programs that install the ?Spy Components? before the EULA comes on. Even if you decide to abort, and do not install the program, the ?Junk? is already ?Spying? on your Surfing habits.
Take a look at this link:
More Foistware? (msbb.exe)
I would say that the best software Firewall is the one that you control
In and Out traffic to the level of each port and application.