You can unlock some cells but you must still have protection set on the sheet.
By default all cells on a sheet are locked when you protect the sheet.
Before you protect it you can select cells you want unlocked and
Format>Cells>Protection. Clear the "locked" checkbox.
Now Tools>Protection>Protect Sheet.
With XL2002 there are a whack of options you can set for a protected sheet.
Gord Dibben Excel MVP