Should I be afraid?

Is my computer safe or not? I use the web a lot, although I usually visit the same favorite websites. On occasion I also use some p2p-software. I don't have any security related hardware (firewall, router etc). I use Windows XP SP2, Firefox and Thunderbird. I have the following security software running all the time:

- NOD32 2.12.3 (default settings, but will probably change to Blackspear's)
- Kerio Personal Firewall
- Giant AntiSpyware

So, is this enough to keep me safe? If not what other program(s) should I have running at all times? A program especially for trojans? I have noticed that some people here use a ton of different programs, but I don't want to have too many programs running at the same time. This means I would like to have suggestions that include a maximum of four programs. You may exchange any of my programs except NOD32.