In spite of mfk's well formulated argument above, I must disagree. Legacy free boards are not necesarily a disaster waiting to happen - no more so than a standard legacy board anyway. You simply have trade-offs.

You sacrifice some compatibility (say with Linux) for speed. A Firewire (400 MB/s) or USB 2.0 (480 MB/s)port certainly has a higher band than a serial (11 pin, 115200kb/s) or parallel (25 pin, 1200kb/s) port. Also, smaller cable equates to less clutter behind the box (a small point really, but it is something to think about). You can clearly see the speed advantages. Networking over firewire is realistic, whereas parallel networking is slow and lagged. Sure it works for your printer, but anything else? As far as the modem, considering how pricy Legacy Free boards are currently, if you're paying for a legacy free system you can probably afford cable internet.

Another advantage USB has over Serial/Parallel is that the USB CONTROLLER takes up one IRQ. You can (theoretically) hook up to 127 devices to the USB controller and still use only one IRQ. This aids in the elimination of the PS/2 port because a)USB keyboards and mice are readily available and inexpensive and b)you can fit 4 USB slots in place of two PS/2.

As far as the "hilarious" complaints Microsoft fabricated for their article, one must realize that - sadly - this is what the average computer user thinks (ok, maybe not to the extreme of "I will never update my hardware again", but you get the point). A standard user will give up quickly if something isn't easy. And I'll be damned if I haven't had jumper problems because the diagrams were shit on at least 1/3 of all the hard drives I've ever owned :)

Really, one wouldn't have to eliminate floppy drives, game ports, or have internal modems. Many external 56k modems do come with USB connections. You can have a floppy drive - you'll just want it to be serial ATA (I know that's not really reasonable, but there's always ZIP discs to replace it), but it doesn't really matter what Microsoft says, no intelligent board maker will kill the floppy drive (Abit's "Legacy Free" boards all have a floppy channel). Most sound cards come with game ports on them, no need to worry about those. And if you're still using ISA slots - it's time to upgrade.

Obviously if you're using a computer that only needs Windows 3.1 or Dos to do what you need it to do then none of this matters, serial and parallel are perfectly fine etc. But if you want the fastest, top of the line schtick, then Legacy Free may not be a half bad idea.
Some current boards that are Legacy Free:

    Abit AT7 / IT7
    Abit AT7-MAX2