You can however flash the drive but it would require hardware to be purchased and depending on a Slim or Phat, you might also need to solder on a QSB or do a drilling hack.
If you're talking about a old Xbox then you should ask a mod to move the topic.
As for softmodding.
You need a hacked save + a game to softmod it.
Mechassault, 007 Agent Under Fire and Splintercell will work.
They CANNOT be Platinum hits since they got the exploit patched.