How to get organization id with organization name in CRM 2011

To get an organization id with organization name in CRM 4.0 we used below

static public string OrganizationId(string orgName)
{
if (organizationIds == null)
organizationIds = new Dictionary<string, string>();
string organizationId = string.Empty;
if (organizationIds.ContainsKey(orgName))
organizationId = organizationIds[orgName];
if (string.IsNullOrEmpty(organizationId))
{
using (CrmService mscrm = CrmServices.MscrmService(orgName))
{
mscrm.Credentials = System.Net.CredentialCache.DefaultCredentials;

ColumnSet cols = new ColumnSet();
cols.Attributes.Add(“organizationid”);
QueryExpression query = new QueryExpression();
query.ColumnSet = cols;
query.EntityName = EntityName.organization.ToString();
BusinessEntityCollection bec = mscrm.RetrieveMultiple(query);

organization org = (organization)bec.BusinessEntities[0];

organizationId = org.organizationid.Value.ToString();
organizationIds[orgName] = organizationId;
}
}
return organizationId;
}

This has changed in CRM 2011 API and we can use query below to get an organization id by passing an organization name

static public string OrganizationId(string orgName)
{
if (organizationIds == null)
organizationIds = new Dictionary<string, string>();
string organizationId = string.Empty;
if (organizationIds.ContainsKey(orgName))
organizationId = organizationIds[orgName];
if (string.IsNullOrEmpty(organizationId))
{
using (OrganizationServiceProxy service = CrmServerConnection.GetOrganisationProxy(orgName))
{
QueryExpression qe=new QueryExpression(“organization”);
qe.ColumnSet =new ColumnSet(new string[]{“organizationid”});
qe.Criteria.AddCondition(“name”, ConditionOperator.Equal, orgName);

EntityCollection orgs = service.RetrieveMultiple(qe);

if (orgs !=null && orgs.Entities.Count>0)
{
var org = orgs[0];
organizationId = org[“organizationid”].ToString();
organizationIds[orgName] = organizationId;
}

}
}
return organizationId;
}