Specifically, legacy-free refers to a mindset of PC hardware design. The reasoning behind legacy-free is that older ports are too slow and clunky to use, and USB technology is the way of the future, and actually put the U in USB to use. Legacy free, supposedly, will reduce OEM support costs.
To illustrate the legacy problem, Microsoft has provided some hilarious examples. (http://www.microsoft.com/hwdev/platform/PCdesign/LR/Lfinterface.asp)
Add a Hard Drive
Legacy: I ran out of hard-disk space because I had too many MP3 files. I tried to install a new hard drive on my computer, and 12 hours later, I finally got the jumper configured correctly and it worked.
Add a Color Printer
Legacy: I have a collection of digital photos that I wanted to print. So I bought a popular parallel port color printer. I plugged it in, and it didn’t work because of some problem with the parallel port not being detected properly. I couldn’t get it to show up properly in Device Manager. I remembered that someone told me to switch my parallel port to ECP mode because of another device I had. So I went into the BIOS settings and switched it back to EPT mode. After a little more time configuring, I finally got it working. Boy, am I glad I work in the computer industry and understand this stuff!
Legacy-free computers, as specified by Microsoft, must lack the following.
- Floppy drives: because every computer is connected to the Internet and you can just e-mail your document or burn it on a CD.
- Serial ports: because everyone uses internal Winmodems now.
- Parallel ports: no need for something THAT big
- PS/2 ports: PS/2 ain't hotpluggable, so out it goes. Ironically, Windows 2000 SP3's lists of bugfixes include "PS/2 hotplug support"
- Game/MIDI port. Creative, to some extent, has done this already on the SoundBlaster Audigy, by putting the game port on a seperate adapter.
- ISA slots, obviously
Legacy-free computers are a disaster waiting to happen, really. The 'dumb' nature of the USB port forces the CPU to waste time doing what would normally be done in hardware (like, for example, UART for serial ports). If your computer goes tits-up, PS/2 will just work, but USB drivers are one of the first things to go wrong with a computer.