OpenDNS works well because it is not software.  With just a minor change to your home wireless router's DNS numbers you can be protected.
There is NO installation required on computers, iPads, etc. and all devices that connect through your router are protected.  Plus, it's free

Note: this is a website blocker but it's not a spam blocker.

How

1. Sign up here for OpenDNS Home.

2. Use these directions to change your router's DNS numbers to these numbers: 208.67.222.222 and 208.67.220.220
(You will need to know your router's admin password.  If you don't know it, it's probably still the default setting from the manufacturer).

(Usually you can browse to http://192.168.1.1  to adjust these settings)

3. Then go to the OpenDNS Settings area to configure the filtering settings you want. (see picture below)

Note: This is a ‘last resort’ fix that immediately turns off a frozen Mac without saving anything.  Normally you should click Shutdown on the Apple menu.

1. On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.

2. Release all the keys and the power button at the same time.

3. Press the power button to turn on the computer.  Note: The LED on the MagSafe power adapter does not change states or temporarily turn-off when you reset the SMC.

And just fyi, here is what those function keys are for:

Either way you will quickly notice that certain keys and the ability right-click are missing!

Summary

http://support.apple.com/kb/HT1220

Also, if you want to use the Windows F1 to F10 keys without pressing Fn you can adjust the Boot Camp Control Panel as shown here:

Key mappings for Microsoft Windows features

Below is a chart of keyboard functions specific to Microsoft Windows, and equivalent key combinations as they are mapped to Apple keyboards by the Apple Keyboard Support driver

Sample MacBook Pro built-in keyboard with a Windows keyboard below

.

 

Function	PC keyboard	MacBook Pro built-in keyboard
Print Screen
Print active window	--
Scroll Lock
Pause/Break		--
Backspace delete
Insert		--
Number lock
Alt (Option)
Enter
AltGr / Alt GR	(Right Alt key)
Forward delete
Applications		--
Windows logo (Start menu)

 

Key mappings for Boot Camp features

Some keys are only available on a keyboard designed for Apple computers. They are either named differently or simply not available on a Windows-compatible keyboard.

Your Apple keyboard provides certain keys that are not available on Windows/PC keyboards.

Function	PC keyboard	MacBook Pro built-in keyboard
Brightness down	--
Brightness up	--
Volume down	--
Volume up	--
Mute	--
Media eject	--
Media eject secondary optical drive	--
Delete	--
Fn (Function)	--
Display Mode Toggle	--
Keyboard Illumination Toggle (MacBook Pro)	--
Decrease Keyboard Illumination	--
Increase Keyboard Illumination	--

Numeric keypad mappings

Apple external and built-in keyboards provide the same functionality as Microsoft-compatible numeric keypads.

To enable numerical input, press Num Lock on a PC keyboard, or Fn-Numlock on the MacBook Pro keyboard.

The chart below shows equivalent keystrokes.

Function	PC keyboard	MacBook Pro built-in keyboard
Page Up		(Numlock off)
Page Down		(Numlock off)
Insert		--
Decimal Point		(Numlock off)
Delete		(Numlock off)
Up arrow		(Numlock off)
Down arrow		(Numlock off)
Left arrow		(Numlock off)
Right arrow		(Numlock off)
Home		(Numlock off)

Additional Information

Note: If you disable the Apple Keyboard Support driver in Windows, Windows will not recognize extended Function keys, nor the (Fn) key.

If you use Rethinkit Exchange hosting, use the following screen as a guide.
Change the highlighted settings (all other tabs and settings have been left at default values).

Also, Entourage uses “identities” as a way of setting up multiple people on the same machine (much like “profiles” in Outlook).

If it is appropriate, you can set up the new Exchange account as a new “identity” and switch to it as needed.