Firewall

[Jason M Evans]

  We've been having virus trouble on our network, so I set my computer
as the host and I've been staying on the Fedora side of my partition.  I
downloaded and printed some firewall tutorials, but it's hard to
understand (I'm new to Linux).  Can someone help me set up a good
firewall?  Also, is it possible to set up a Linux firewall that will
work even when my Windows side of the partition is booted instead?

Also, if it's okay to ask two easy questions in the same posting, here
they are (let me know if I should post separately):

[I have searched for these answers to no avail]

  How do I set Evolution to automatically Send/Receive upon program
start?

  How do I change the color of windows in Fedora, the gray inside part
of windows?  

Thanks, this is exciting.  I am pursuing an MIS degree and planning to
pursue Red Hat Certification.  I am excited about my long adventure. 
[just a bit of introduction]

Jason.