Which programs do I need? Firewall? Anti-virus? Network Magic? Are there alternatives to the 30 day trial programs that come with the machine?
It needn't be expensive at all.
As far as a firewall goes, I use Zone Alarm.
It's free if you only want a fire-wall and it takes a wee bit of "teaching" to get it to allow or deny access to different applications.
With respect to Anti-Virus software, I've been using Avira Anti-Virus
for some years now and although it does have a nag screen that comes up when it updates itself, you can just click it away.