TeamXBR along with talented members of xboxhacker.net has been active with XBReboot lately and managed to fix the freezing/lagging issues when playing games from the Xbox 360 hard drive. Also several other bug fixes for the supported motherboards makes XBReboot stable enough to please most users. I think there will be lots of people attempting the JTAG Hack in the near future. If you need help to get started there are tutorials available in the download section. Just keep in mind that you shouldn't connect to live using the hacked kernel, unless you want to be banned.