Systems Management

You can use a generic password in the unattended file and then change it as a post task if you think the special character is your problem.  I have an ! as a special character in my answer file, I use the waik and set the plaintext to false.  Since you are using Kace there is a wizard they supply also for this.  the link is on the k2000 tools page.

</OOBE>
            <UserAccounts>
                <LocalAccounts>
                    <LocalAccount wcm:action="add">
                        <Password>
                            <PlainText>false</PlainText>
                            <Value>VwBpAG4AZABvAHcAcAHMAcwB3AG8AcgBkAA==</Value>
                        </Password>
                        <DisplayName>F15Master</DisplayName>
                        <Name>F15Master</Name>
                        <Group>Administrators</Group>
                    </LocalAccount>
                </LocalAccounts>
                <AdministratorPassword>
                    <PlainText>false</PlainText>
                    <Value>VwZABvAHcAcG0AaQBuAGkAcwB0AHIAYQB0AG8AcgBQAGEAcwBzAHcAbwByAGQA</Value>
                </AdministratorPassword>
            </UserAccounts>
            <RegisteredOrganization>tmcc</RegisteredOrganization>
            <RegisteredOwner>staff</RegisteredOwner>
            <AutoLogon>
                <Password>
                    <Value>VwBpAG4AZABvAHcAcAHMAcwB3AG8AcgBkAA==</Value>
                    <PlainText>false</PlainText>
                </Password>
                <Enabled>true</Enabled>
                <LogonCount>3</LogonCount>
                <Username>F15Master</Username>
            </AutoLogon>
        </component>

http://www.itninja.com/blog/view/sysprep-creator-wizard

to change it as a post task use:

net user username newpassword

Update:

I kept having trouble with creating the unattend in WAIK differentiating between Adminstrator account (built-in) and my own company admin account, we will call MyCompanyAdmin.

Part of the trouble I was having was that our admin password contains special characters and it took some digging to figure this out. I learned a little about XML but basically an ampersand in plain text needs to be indicated in XML so that the unattend file doesn't interpret an XML command and then get a parsing error from the '&' symbol.

Ex: My&password becomes My&password

My latest attempt was:

Install Win7
Enter Audit mode
Software installs, updates, configs
Create MyCompanyAdmin account
Set Administrator account to login 5 times.
Set Windows activation
Set domain login with special domain account with only domain addition permissions. No special characters, just uppercase, lowercase, and numbers for a username and password.
Run sysprep executor.

Aftermath:

The computer is not joined to the domain. (Working on a Kace post-installation script in the meantime.)
MyCompanyAdmin account exists and is not longer locked, disabled, or password FUBAR.
Windows is activated
Administrator account is still enabled. Perhaps I have to play with some more reboots to see if after the indicated 5 logins from the sysprep creator,  it automatically disables.

Kicker:

After all my updates were run up to running sysprep, the machine comes up with 8 more updates available.

Sonofa...

Are you using a deployment system? I would create the account in a reusable manner like a task sequence or something like that, that means you can reuse it later. Having it in the image means if you need to redo it, you need to make the image again. I guess if your using an unattend, then that would be ok, but not ideal.