Here is the top section of the Evox.ini file.
[Misc]
AutoLaunchGames = No
AutoLaunchDVD = No
DVDPlayer = "E:\Apps\players\dvdx\default.xbe"
AutoLaunchAudio = Yes
#AudioPlayer = "c:\msxboxdash.xbe"
MSDashBoard = "c:\msxboxdash.xbe"
Look in your C drive and see what the Xbox Dash may be named. It could be like above, or named MSDash.xbe or Xboxdash.xbe. Change the above line in Evox.ini to the name of the file on your Xbox.
As for putting in a larger HD, that would depend on the modification. When you boot the Xbox does it have "Microsoft" under the flubber screen or do you see something else on the screen too? Sometimes with a mod chip or a TSOP Flash you will see another logo on the screen or in place of the "Microsoft".
If you can't tell from that screen, look on the left side under the DVD drive. Do you see any lights? If so it is from a mod chip.
With a mod chip you can put in another drive and use Slayer's to make the drive work in the Xbox.
With a softmod you will need to back up the eeprom and FTP it and the C and E drives to the PC and use Xboxhdm to build the new drive. You could use Chimps to clone the drive with the Xbox too.