I need to know how to hookup a USB Key board and mouse to my XBOX360
so I can play first person shooter games like I do on my PC

I have an xbox 360 at home with Perfect Dark Zero, Quake 4, and Call
of Duty 2.  I have used my Playstation 2 USB keyboard to type answers
to peoples' messages in the XBOX360 OS, and that the OS doesn't
support the mouse (and neither does the FFXI Beta seem to).  I'll see
if either of the FPSs I have supports mouse/keyboard control in about
twelve hours or so and post back.

[On Playstation 2, I used my keyboard and usb mouse to play Half-Life.
 I am pretty sure that other games support them also, but I haven't
tried using them with Red Faction, Unreal Tournament, or Quake 3.)

I tried using the mouse and keyboard with Quake 4, but it didn't work.
 I read some BBS posts which suggested support for keyboards and mice
isn't allowed on XBOX360 because that would be unfair to the
controller people in multiplayer*.

I didn't make an effort to try the other games. :(

*(Which would be something I'd totally agree with, since I got totally
owned by a bunch of people on standard xbox live who had mice adapters
in Halo 2 :/)

I am sure Third-party manufactures will find a way around this

not tu b rude but
have u ever tried hooking up the USB keyboard/mouse  thru the USB
ports on the 360 if any

That really suxs, another reason NOT to get an XBOX 360