Can I set different passwords for different sheets
1. Open a blank worksheet in Excel 2007.
2. On the Review tab, click Allow Users to Edit Ranges.
3. In the Allow Users to Edit Ranges dialog box, click New.
4. In the New Range dialog box, click Collapse Dialog, select the range B2:B6, and then click Collapse Dialog again.
5. In the Range password and Confirm Password boxes, type rangeone, and then click OK.
6. Repeat steps 3 through 5. However, select the range D2:D6, and then type rangetwo as the password for that range.
7. In the Allow Users to Edit Ranges dialog box, click Protect sheet.
8. In the Password to unprotect sheet box, type ranger, and then click OK two times.
Note Retype the password when you are prompted.
9. Select cell B3, and then start to type Dataone.
Note When you start to type, the Unlock Range dialog box appears.
10. Type rangeone in the Enter the password to change this cell box, and then press ENTER.
Solution 2
1. Open a blank worksheet in Excel 2007.
2. On the Review tab, click Allow Users to Edit Ranges.
3. In the Allow Users to Edit Ranges dialog box, click New.
4. In the New Range dialog box, click Collapse Dialog, select the range B2:B6, and then click Collapse Dialog again.
5. In the Range password box, type rangeone, and then click OK two times.
Note Retype the password when you are prompted.
6. Repeat steps 3 through 5. However, select the range D2:D6, and then type rangetwo as the password for that range.
7. In the Allow Users to Edit Ranges dialog box, click Permissions, and then click Add in the Permissions for Range2dialog box.
8. In the Select Users, Computers, or Groups dialog box, type Everyone, and then click OK two times.
9. In the Allow Users to Edit Ranges dialog box, click Protect sheet, type ranger in the Password to unprotect sheet box, and then click OK two times.
Note Retype the password when you are prompted.
10. Select cell B3, and then start to type Dataone.
Note A password is required to edit the cell.
11. In the Unlock Range dialog box, click Cancel.
12. Select cell D3, and then type Datatwo.
Also see here