SP2010: How to check if current user exist in given AD group?

I have users who are on a AD group (ADGroup1) and I have a sharepoint group (SPGroup1) which has the above AD group . My question is: how do I check if current user is member of given AdGroup?

private Boolean isUserInGroup(SPGroup oGroupToTestFor, String sUserLoginName) 
    {    
        Boolean bUserIsInGroup = false; 
 
            SPUser oUser =null; 
            try{ 
                oUser = SPContext.Current.Web.AllUsers[sUserLoginName]; 
                } 
            catch{} 
            if(oUser!=null){ 
            foreach (SPUser item in oGroupToTestFor.Users) 
            { 
                if (item.UserToken == oUser.UserToken) 
                { 
                    bUserIsInGroup = true; 
                    break; 
                }                     
            } 
            } 
        return bUserIsInGroup;  
    } 

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(http://stackoverflow.com/questions/1063931/sharepoint-check-if-a-user-is-member-of-a-group)

does not work if user exist on AD group (ADGroup1) which exist on sharepoint group (SPGroup1).

EDIT: This (http://chrissyblanco.blogspot.fi/2007/07/determining-whether-user-is-member-of.html) seems to be the answer.