New Apple user HELP

I switched. Got a 17inch Imac and FINALLY I can get sleep and not have to worry about Wincrap machine...Life is easy, life IS Mac.

Now,
I was wondering if I "really" need these 2 programs.

1. Virex
2. Disk Warrior

I am running OSX Panther and will not being using programs like Limewire. I also heard Panther has defrag kinda built in.

PLEASE can anybody tell me what programs (3 at least)are a MUST...I am a Developer and Have Adobe Suite and Macromedia Suite already. But for utilities and all.

Thank you all.

Virex, no esp if your going to stay away from p2p. (No harm in having it, but Apple viruses don't exsist for the most part. Ones that do Apple usually takes care of in Updates.)

Disc Warrior, heard of it but my mind is blank can't remember what it is. If its a disc-cleanup like app then I'd go with Mac Janitor or Onyx.

As far as Disc Defrag on Panther. I don't own Panther, but I haven't heard of such a thing and don't see it on "reasons to switch to panther" or "whats new about panther" I'd think Apple would be showing that off since that is something Mac users have wanted. But if it is news to me, and I'll be upgrading soon so good news too!