modchip help

[toviolent]

Ok this is my first time messing with this modding stuff and Im looking for some answers to my questions if anyone could help it would be appreciated and I did do a search and couldnt find all the info I was seeking. Here is the questions if you can help thanks.

1. If I already own an xbox can I send it somewhere to get modded I have seen places that sell them premodded but are there places that will mod them if you send them in if so what are some reputable places where I can send it.

2. I've never flashed a bios before so what mod chip would be the best for me . Do they come with a bios on them if not is it hard to do? I would also like to play live once in awhile what chip has an external switch

Thanks for any help in advance