Yup, I would say anything 4GB and up would need 64bit. Server is able to use full resources available under 64bit.
UKDirectHost: Dedicated Servers in the UK, USA, Germany, France and Netherlands. Cheap Dedicated Servers | PEER 1 Partner Payment Methods: Credit/Debit Cards, 2Checkout, UK Bank Transfers, Moneybookers. FraudRecord, a collaborative effort to keep track of bad clients. Protects you from known spammers and fraud.