Okay, well it all depends on the type of moddong that you want to do.
Pretty much all of the "cool" mods require a JTAG'd xbox. Here's a list below of the known mods with a JTAG xbox.
1 kill 1 prestiege
speed
gravity
global thermonuclear wa
rchopper gunner bullets
god mode
JTAGing requires a xbox, soldering skill, and a hard drivr transfer cable.
As always there is of course a risk. And logging in to live with a JTAGd xbox will get you console banned within a few hours to 1-9 days. If your lucky two weeks.
Other mods such as the gamer tag mod only require afew programs and a hard drive transfer cable.
Risks of gamertag mod is xbox live ban I believe.
All other "mods" such as private match xp. Are technically glitches and will not get you banned.
Hopped I could help -A E I 0wnz U
魔羅多花屋多羅多羅多羅なら畑ばかりばあ畑な

Well first call up Microsoft and tell them you would like one of those data transfer kits that "your friend told you about" and they will ask for your Xbox serial number.

Congratulations, you can mod any game now + other stuff.