You will probably need to use LDAP for that bit of code. I don't have AD @ HOME either - this bit of code is totally un-tested - its just a quick conversion ...

 Code:
Break On

$= SetOption("WrapAtEol","On")

$objSysInfo = CreateObject("ADSystemInfo") 

$strUser = $objSysInfo.UserName 

$objUser = GetObject("LDAP://" + $strUser) 

?"Your account expires on " + $objUser.AccountExpirationDate + "." 

Exit 0