Note:  Not a hacking tool... just to make sure no one gets confused there.

But, for any of you who like me are given the task of slipstreaming service packs into install cd's for your work... it's a nifty tool.  It is one of the niftier little tools I have come accross, since I'm one of those minimalists who likes to get rid of all the cr4p that M$ insists on bloating their OS with.  According to the site: 

http://www.nliteos.com/nlite.html

Features
Service Pack Integration
Component Removal
Unattended Setup
Driver Integration *
Hotfixes Integration **
Tweaks
Services Configuration
Patches ***
Bootable ISO creation

* - Textmode (CD Boot) and normal PnP
** - hotfixes with white icons, *KB*.exe, including update packs
and Internet Explorer 7
***- supports generic SFC, Uxtheme, TcpIp and Usb Polling patching.

My experience has been that it works very well.  You can impliment various registry tweaks (like the loved removal of timestamping) and such.  I think the registry tweaking portion is what got me.  That... and being able to make ISO's without MSN, Winblows tour, or File and settings transfer wizard... or any of that cr4p in it.  You can make a very trim and customized install disk for either XP or 2003 with it, or a very trimmed down gamer install... yes... I did that too.  >> 

I have used nLite many times, its a good bit of kit.
Just for completeness, if your a Vista user then vLite is for you.

I have only used this once, but very similar to nLite for XP.

http://www.vlite.net/