Windows Server 2003 requires Secure and complex password. If you want to disable this policy you must follow these tasks

1. Go to the management console:
2. Start > run > type MMC > enter.
3. Click on file > add/remove snap-in.
4. In the add/remove snap-in window click the add button.
5. In the Add standalone snap-in window scroll down and highlight Group Policy Object Editor and click add.
6. In the Select Group Policy Object window make sure or browse and choose the Local Computer group policy object is chosen and click finish. click close then click OK for the next to boxes.In the console window, expand Local Computer Policy, expand Computer Configuration, expand Windows Settings, expand Security Settings, then expand Account Policies.
7. Setting for 5 try’s for a correct password is under the Account Lockout Policy and Setting for not use a complex password structure is under Password Policy.This would be for the local machine. If the users are logging into the domain then you will need to change the Domain group policy.