Excel Data Protection- AKA: Sheet/Macro Password Protection

Hello-

Any advice for best practices for protecting data/methods/macros within
Excel? Clearly, password protecting a sheet isn't the best security (free
utilities to crack it).

Scenario:
- I need users to be able to access the workbook, but by no means, gain
access to data within the certain sheets
- I can hide the data by utilizing similar colored text and hiding the
rows/columns
- Once the password is created, it appears there are tons of free utilities
that remove these passwords- Bummer.

Question:
- Any advice to help prevent the utilities from doing this? More complex
passwords help?
- Any best practices to prevent would be scoundrels from gaining access to
this data if they do crack the sheet passwords? (unfortunately, the sheets
are calculating data so having a feed from outside won't help)
- Any idea if this 'problem' has been addressed in office 2010? (aka: better
sheet password protection)

Many thanks for the tips, tricks, thoughts on this subject.