Give me advice on security

Well there you go, I never had any problems with any viruses and didn't own a virus software either. I guess I was lucky.
But........anyones luck has to end one day and it did. We are running 3 family computers at home, all on win98 and a
homenetwork, 2 computers are hooked on the internet via dialup, and one is not on the internet. But we had all 3 infected with
the pe_funlove.4099, one was infected additionally with the pe_spaces and two of the opa virus's. We spent the
last 2 days scanning/removing/reloading etc. I hope we got rid of them, but who knows for sure.
Now, I need some down to earth advice here, not so much about the particular virus's, I saw there was another post
about the same problem, but more about security.
Honestly, I don't want to go overboard with a million programs running in the background trying to protect me and
slowing my computer down to the unbearable, our internet connection is slow enough with 33,6 kbps at the most.
But I do want to do something to save me more grey hair when it comes to virus/hacking etc.
So what do I need, Firewall, Virusscan what else.
Does a firewall have to be updated like a Virus software? Which Virus software do you think is best? I heard that
pc cillin is too complicated, McAffee too memory hungry, there is symantec, I heard good things there, but of course
that is all bias to other peoples experiences with them.
Give me some more informed opinions, of course, money matters too, if I can get it cheap.......the better, or even free?
I know I'm asking too much.
Anyway, give me some more ideas to think about.
And what about adaware, somebody suggested that a while back here at the techguy's posts I had, but now I read it is outdated
and the adaware 'maker' abandonded it? What program would be there to replace it?
Thanks a bunch.