If this is the hotel you're talking about:
http://www.professionaltravelguide....Hotels/Reviews/Okura-Chiba-Hotel/Map-p1043547
It looks like it's pretty close to Chiba's Chuo station, which you can get to with just one transfer (
link). As long as you don't have a lot of luggage this is probably the cheapest and easiest way to go if there are no limo buses.
In case the link doesn't work, you'd be taking the
Keisei Main Line (京成本線, keisei hon-sen) from Narita Airport (成田空港, narita kuukou)
to Keisei Tsudanuma Station (京成津田沼駅, keisei tsudanuma eki). This should take about 40 minutes.
Then transfer onto the Keisei Chiba Line (京成千葉線, keisei chiba-sen)
to Chiba Chuo station (千葉中央駅, chiba chuuou eki)
And snag a cab to your hotel. You can just show them the name and address of the hotel and they'll get you there. It's not too far. You're looking at 840 yen for the train, and probably another 500-600 yen for the cab ride.