No one, as of yet, has found a way to run two programs at one time on the xbox... That means, an xbe firewall is out of the question unless you want to come up with a way yourself to run two programs at one time (outside of linux.) It's possible to run WindowsCE now on your xbox (with problems) and everyone said it couldn't be done... That means that eventually, theoretically, you could run Windows XP/98/ME. The easiest option you have is to run the dvd2xbox acl string to stop the "known" live checking string. If this hex value makes it into a bios, (and it could) then that would stop ALL games using that string from connecting to xbox live... The problem therein lies with M$ Dashboard updates... a future dash could (possibly) allow for a secondary call, but it would still have to allow the one used now, otherwise all the current Xboxlive games would not be able to go live anymore. This seams unreasonable because the only reason M$ would do this is to purposefully ban people for modding... Wouldn't put it past them, but come on... this isn't a conspiracy. Has anyone tested this hex replacement to see if it allows system link? I'd rather take the risk of losing live to be able to play system link. and lastly... I set my xbox live account up to use a password (button sequence) the day I activated it. No game that I've played so far has EVER connected to live without asking me for this password. If I "accidently" activate live AND put in my password while the switch is on, then I'm just a freaking retard. (This has not been tested with ALL Live Aware games, but Prince of Persia didn't connect without password.)
Summary:
1. Xbox Live blocking CAN be enabled through the BIOS, but you would need someone with knowledge of how the BIOS is compiled and edited to do that.
2. Put a password on your Live account... It helps!!!
3. UnleashX is the best dash to date.