computer secruity

hi
a number of months ago posted a similar sort of question. what secruity programs and steps i should be taking. i would consider myself of an average pc user.

i am using atm:
avast4.0
comodo fw pro
spybot s&d

and ccleaner to fix registry and clear crap(i am looking for a better registry cleaner, i feel as though that there are quite a number of hidden errors not being picked up.

Is this a good combitnation? i have notice that a few programs overlap.
eg. that all programs seach for spyware. some monitor registry.

i'm just worring about having them clash.
(all free verisons if that helps)

kind regards

Bill ALlen