Windows Media Center DVDs are hard to come by, since Microsoft didn't
plan to distribute them on DVDs. If you want to get Media Center
Edition, then the best thing to do would be to buy a PC with MCE
installed. If you get a DVD it might be pirated, and you will run into
problems. The differences are noticeable. Media Center Edition
includes "Media Center". It allows you to view videos, pictures, and
music. It allows you to watch TV if you have a tuner card. It has a
fairly new theme called "Royale" but you can download it for free on
Microsoft's web site for other versions. It's a nice addition to XP.
Here is Microsoft's Media Center page:
http://www.microsoft.com/windowsxp/mediacenter/default.mspx.
Also, if you buy a PC with MCE installed now, you may be able to
purchase Windows Vista (which has everything that MCE has if you get
the right edition) at low or no cost. To me, that's the way to go if
you HAVE to have MCE.