I have to admit I don't really use anything. I have no antivirus at all (I make sure I don't give my email address to any porn sites

LOL)
Other stuff I do run, though:
- Nvidia ntune, so I can OC my card in Vista
- Windows Defender, which does a good job of blocking most everything
- IE7 with built-in pop-up blocker
And that's about it... don't need anything else

Must have hardware (that never really grows old):
- Saitek Eclipse keyboard (takes a licking and keeps on ticking)
- Logitech MX518 (nice wired gaming mouse)
- Dell 2405WFP (which I sadly no longer have

)
- A good USB sound card (for everday use or emergencies)
- A good pair of headphones (I recommend Koss Porta-Pro)
- A Firewire harddrive (never trust USB with your data)