How can I create a list of all User Accounts?

The best way is to use a utility shipped with the Resource Kit called ADDUSERS.EXE which is used to add users that have been detailed in a text file. This image can also be used to export the current users and groups into a comma separated file. What is a comma separated file? This is just a file that has comma's between fields and when read into a spreadsheet/database, the commas are detected, and the commas are replaced with a new field. The format is :
addusers /d
e.g. addusers /d johnslis.csf
Note: Be very careful not to enter /e instead of /d, /e deletes all users and groups!
This file can then be read into a spreadsheet/database (such as Excel) and you will need to specify that comma is the delimiter.

A utility called USRSTAT.EXE is shipped with the NT Server Resource Kit, and this utility supplies information on all members of a given domain, including time/date of last login
usrstat
e.g. usrstat savilltech

The Resource Kit utility SHOWMBRS.EXE will show all the users in a given group, so you could dump out the Domain Users group of a domain,
showmbrs "domain users"
e.g. showmbrs "savilltechdomain users"
You could add "> " to output to a file, e.g. showmbrs "savilltechdomain users" > allusers.list

Finally if you don't have the resource kit (go and get it), you can use the NET command to show all users in a domain
net user /domain
Which will list all users in the current domain, again you can user > to output to a file. You could then get more information on each user this lists by entering
net user /domain
e.g. net user savillj /domain
You could easily write a perl script to automate this task.

You could also use Windows Scripting Host which gives you the option of being able to be more flexible with the output. The code below just lists the full name

set oDomain = GetObject("WinNT://SAVILLTECH")
        WScript.echo "Domain : " + oDomain.name
        for each oDomainItem in oDomain
         if oDomainItem.Class = "User" then
          WScript.echo "   Full Name=" + oDomainItem.FullName
         end if
        next