Setting up the Correct Permissions on the IIS Server
For NT4 / Win2k
By: Aaron B. Copyright AaronOutpost.com

If you are using an ASP script requiring the ability to write data to a database or a text file then you will need to check the permissions on the server so that you have write and read permissions on that directory, database, or text file.

To check or change the permissions on the server go to Windows Explorer and do the following (for NT and Win 2K users only using NTFS file system, Win9x has no permissions to change):

STEP 1: Right click on the directory containing the database or text file.

STEP 2: Click on Properties

STEP 3: In the dialog box click Security tab

STEP 4: Uncheck Allow inheritable permissions from parent to propagate to this object, from the bottom of the dialog box.

STEP 5: Click on the Add button at the top right of the window.

STEP 6: The Select Users or Groups dialog box will open, highlight IUSR_MyComputer account by clicking on it. 

MyComputer is the name of your computer.  
IUSER is the Internet Guest Account setup by default when IIS is installed on the system.

STEP 7: Click on the Add button in the middle left of the dialog box. 

You should then see MyComputer\IUSER_MyComputer appear in the bottom box 

STEP 8: Now click on the OK button of the Select Users or Groups dialog box.

STEP 9: You're now back to Security Properties dialog box. 

Top box now contains the Internet Guest Account (MyComputer\IUSER_MyComputer)

STEP 10: Highlight the Internet Guest Account (MyComputer\IUSER_MyComputer) by clicking on it in the top box.

STEP 11: Select Read and Write and if need by Read & Execute permissions by checking the boxes. 
(You can check all of them if you want. If you are not worried about any security measures.)

STEP 12: Repeat steps above for any other directories or files that need be.