1) Yes, you can use your DSL modem (or any broadband connection, assuming you have access to the required ports). For information on hooking up your XBox to your network, check the XBox Live site over
yonder. I'd definitely recommend buying a router if you don't have one already.
2) You don't need a memory card, most stores don't even carry the memory card anymore, most games don't support the memory card. Rockwell is right, there are some games that use the memory card if you want to carry characters to a friend's house. These games are becoming more and more rare... first, because most people don't use the feature, and second because there are ways of abusing the memory card feature in some games. I've had my XBox for almost a year and I've never needed one. Virtually all XBox games just save to the hard drive anyway.
3) Good "only on XBox" games... Well, here's a list of the Best of the Best (IMHO):
Halo- The premiere XBox game. Yeah, there's a PC port now, but it's still first and foremost an XBox title. Up to 16 people can play with 4 XBox's connected on a LAN. The best FPS on a console, period. At least until...
Halo 2- Coming in a week. Supposedly superior to Halo in every way. Unlike the original game, this will allow 16 people to play on XBox Live. Expect months of fun from the single-player game, and
years of deathmatch chaos on XBox Live. If you want to get it, reserve it
right now. Two million reserve copies have already been sold.
Knights of the Old Republic (KOTOR)- Yeah, once again, there was a PC port created about 6 months after the original game... Whether you play it on PC or XBox, this is quite simply the best Star Wars game ever conceived. It is an RPG, but less like Final Fantasy and more like Baldur's Gate, if that means anything to you.
Ninja Gaiden- Action-adventure ninja game. A remake of one of the classic game franchises, and a candidate for toughest game made over the past five years. Created by the people who make the Dead or Alive fighting games, the combat in Ninja Gaiden is spectacular, technically challenging, and very satisfying once you master it. On top of that you can download new material from XBox Live... including new enemies, new game features, and new weapons. And hell, you're a
ninja.
Crimson Skies- Kind of a cross between a first-person shooter and a flight simulator. You're a pilot battling other pilots in small World War 2-era planes. You have machine guns, homing missiles, and rockets at your disposal. The single-player game is pretty fun and challenging, but the game's real strength is XBox Live... 16 player battles where all hell is perpetually breaking loose.
And coming soon:
Jade Empire- Another RPG from Bioware, the people who made KOTOR. This one's set in feudal China. You play as a young ninja (woo hoo!) who must battle some evil power or other... Anyway, you fight pretty much every magical and non-magical creature from Chinese legend, up to and including dragons. The combat system is supposed to be really cool. You fight similar to a normal action-adventure game, unlike typical RPGs.
There's other stuff I'm sure I am forgetting. Also, most any game released on multiple platforms is superior on the XBox- faster load times, more features, and vastly improved graphics. It's good stuff.