Vista's personal firewall and AV package

["urandom character special device" <urandomdev () gmail com>]

I am speaking from a consumer level standpoint.

Should I replace Vistas own firewall with a third-party tool? In XP I
used Checkpoints ZoneLab (with AV, anti-spyware, firewall and other
add-ons). Is Vistas firewall (when properly configured for outbound
and inbound) secure? What are advantages and disadvantages of
third-party tools?

If I don't need a complete internet security suite, I only need AV
protection. What do you recommend me for AV? I wish to give Kaspersky
a chance. Are there professional comparisons these products?