Depends on what you want really.
If you want XBLive then don't go for a RGH.
If you don't care about XBL get a RGH.
As for a guide for Drive flashing.
You'll probably want an Xkey (cheaper and easier)
Depending on your drive, you'll need a RGH anyway to obtain the needed files + Drive key.
As for RGH.
Use JRunner and its user guide.
For Flashing, Refer to the Jungleflasher guide.
Both guides come with the download.
However, and this is what I reccomend.
if you can't solder tiny points on a Mobo, pay someone to let it do it for you.