First of all you need a modded xbox.
That means it's been either fitted with a mod-chip or soft-modded (ie. a vulnerability has been exploited). That'll enable your xbox to play dvd-rs or original games from any region. I suggest you find an electronics vendor, who supply this service, since that's the easiest solution for anyone new to the world of modchips. The operation takes no more than 30 mins, and isn't costly.
Some people also like to add a bigger HDD once their XB has been chipped, this is not necessary if you just wanna play emulators tho'
Secondly you need to state which systems you're interested in emulating, since the list of XB emulators is long. See for yourself (note! most of these are ports of PC emulators);
AdamX - ColecoVision/Adam Emulator port for XBox.
ArnoldX - Amstrad CPC
AtariXLBox - AtariXLBox is a Atari 800/5200/130/320/XL/XE
BlissX - Intellivision
BlueMSXBox - MSX/MSX2/MSX2+
Bochs - x86 (PC)
DGen - Sega Genesis
DOSXBox - DOSBox (286/386 PC Emulator)
Daedalus X - N64
DaphneX - Laserdisc Arcade Emulator (yes it pålays Dragon's lair
Dega-X - Sega master system and Game Gear
DegaBox - Sega Master System / Mark III / Game Gear
DreamSPEC - ZX Spectrum
FBA-X - FBA (arcade emulator for CPS-1& CPS-2 arcade hardware)
FBA-xxx Pro - FBA (emulator for MC68000/Z80, neogeo, cps2 and cps1 based arcade games).
FCEUltraX - NES
FMSXBox - MSX/MSX2/MSX2+
Frodo-X - C64
FuseX - FUSE (Free Unix Spectrum Emulator).
Gens-X - Sega Mega CD, 32X & SRAM(BRAM)
Gens_xport - Sega Genesis/Megadrive/32X/SegaCD/MegaCD
Gnuboy - Gameboy/Gameboy Color emulator
HuGoX - PCE
KI-Emu X - Killer Instinct 1 and 2 arcade emulator
Kaster-X - SEGA MASTER SYSTEM
Kawa-X - Capcom CPS1, CPS2 and SNK NeoGeo emulator.
KegsX - Apple IIgs/e/c/+
Koleko-X - COLECOVISION
LynXBox - Atari Lynx
MAME-X - MAME
MAMEdOX - MAME
MAMEoX - MAME
MednafenX-Lynx - Atari Lynx
MednafenX-NES - NES/Famicom Disk System/VS UniSystem
MednafenX-PCE - PC-Engine/TurboGrafx-16/SuperGrafx/Arcade Card CD/CD/SCD
MekaX - Sega Master System/Game Gear/SG-1000/SC-3000/SF-7000/MK3 NeoCD/SDLx - NeoCD/SDL neogeo CD emulator.
NeoGenesis - Sega Genesis/Megadrive/32X/SegaCD/MegaCD Emulator
NeoPop-X - NeoGeo pocket color
NeoPopX - see above
Nester X - NES
OdysseyX - Odyssey 2
Oswan-X - Wonderswan
PCSXBox - PS1
PJ64-X - N64
SC3X - SEGA SG-1000
SMSPlusX - Sega Master System
ScummVM Xbox - Allows playing games based on LucasArts' Scumm (Script Creation Utility for Maniac Mansion) system.
ScummVMx - See above
Snes9x X - SNES
SpeXtrum - ZX Spectrum
Stella - Atari 2600
Surreal64 - N64
U64-X - Killer Instinct 1 and 2 arcade emulator
UAE-X - Amiga
Uvba - Game Boy Advance
Vice20X - VIC-20
Vice64X - C64
VicePETX - Commodore PET
WinSTonX - Atari ST
WinUAEX - Amiga
WonderSwanX - Wonderswan
XBoyAdvance - GBA/GBC/GB/SGB/SGB2
XMugen-linux - XMugen–linux is not an xbox port of M.U.G.E.N, it’s a mini linux distro reduced to it’s minimum in order to launch mugen on Xbox.
XNES - SNES
XPCE-X - PCE
Xenesis - Sega Genesis/Megadrive, 32X and Sega CD
Xthom - thomson to7-70
Xvectrex - Vectrex
Xzx81- ZX81
Z26X - Atari 2600
ZsnexBox - SNES
eXtremeGB - Gameboy/GBC
So when you're XB is ready to read DVD-Rs, and you have decided which emulators you want to try, feel free to come back here, and we'll help.
BTW:
FTP = File Transfer Protocol. In short you connect your XB to your PC and transfer any files you want to.