newbie help!

I just installed Linux Mandrake 7.1 and I used the automated install as
every time I tried the customized something went wrong and it would not boot
completely.
I'm to new to troubleshoot so I took the easy way out but now I am
overloaded with hundreds of packages that I really dont want as of yet. I am
really concerned with security as I am on a cable modem any suggestions for
firewall/router that is effective in a two computer Lan.
Thanks in advance,
John