with the linux/007/memcard exploit you can flash a new bios to the xbox without the need for a modchip....but you need to bridge two very small jumpers....I MEAN SMALL!!, i was going to do it (just for fun, i already have a matrix mod) but those points are damn small...if you've got the balls, skills, or know someone that does it's a no-brainer... Of course if you overwrite the xbox's bios with a hacked one so you can play "backup" games then you will not be able to connect to xbox-live, and if you screw up you will be forced to buy a modchip in order to use the xbox.
I got my matrix(xodus) chip from easybuy2000, it did indeed take 3 weeks, but that's when it was expected and told to be delivered by....there weren't any tricks about it.
As to wanting the 1meg space vs. the 256k, it's nice to have, but the majority of the bios files out there are 256k....
And above all...make sure you know what you are doing before you jump into something (knowing what the name of the product is, before you go and buy it, would do for starters) research, research, and research again...then make a decision