Virtualization technology brings great conveniences to cluster and data center management. By using this technique, we can reconstruct a new computing environment quickly and easily. Compared to the traditional cluster environment, load balancing in a virtualized environment needs to address several new problems. This paper focuses on live migration strategies for load balancing in the virtualized cluster. We first divide the whole balancing process into three sub-problems, namely, the selection of the VM being migrated to, the choice of destination host and the determination of the migration execution sequence. Then we perform a series of experiments to investigate the particular features of the live migration of virtual machines in the balancing scenario. Based on our experiment results, we propose an informed live migration strategy which includes affinity-aware decision making and workload-aware migration to improve the efficiency of configuration of the virtualized cluster.