APC Magazine published an interesting article on TinyXP. Here's a taster:

The driver packs are 146MB of OEM-style driver bundles, supporting a wide range of hardware from broadband modems and LAN adaptors to base chipset, storage and audio. It even has VMWare virtual device drivers. Interestingly the one hardware group which isn't targeted is graphics hardware - presumably as the driver packs don't contain any associated application bundles (like Catalyst Control Center), the makers decided it was best to let users download the latest drivers after installation...also, graphics driver downloads are huge.

The idea is that you can use TinyXP to install XP on just about any hardware platform and get at least enough functionality to be up and running straight away. This is a very useful approach - building a new desktop image using Windows XP these days means you need another computer to jump online and grab the latest drivers - rather like troubleshooting every Linux distro in existence.

All the OS setup options include SP3, drivers up to May 2008, DirectX, Flash player and the Royale theme from Windows XP MCE. The BARE option is a seriously stripped-back installation of XP - no themes or games and minimal services, but there's still enough functionality to support all hardware types, and the system footprint is tiny - only 50MB of system RAM is used on a fresh install (compare THAT to Vista.)