I'm looking for the easiest way to get an Image of a WinXP and Win7 system (completey configured and all needed software installed), and then be able to load the image on to an USB stick to install those Images through the stick to other clients.
So I just need two sticks, one for XP one for 7, which I can plug in to a new client, boot from stick and install the Image.
You can check into using MDT 2010 (Microsoft Deployment Tool). You would need to load your image into the software and then have it create bootable media which allows you to select USB or ROM.
Another option would be to use the WAIK (Windows Automatic Installation Kit). You would capture your image using the 'imagex' application provided and create a WIM. From there you would need to load the WIM again using Imagex.
The devices will mostly be hardware specific, so if you want to install an XP system on multiple different hardware platforms you'll most likely end up with blue screens. Windows 7 will be more forgiving.