Yeah, as someone with a JTAG and an original XB, I say don't JTAG/RGH if all you care about is original XB games. They'll run, but BC is not the greatest, lots of glitches and stuff. Get an actual XB and you'll be much happier..
If you were going to do something else with the 360 like usb loading or homebrew or whatever, go for it though.