The new LXL-ABR-4500 features ports on the back while the LXL-XBR-4500 features ports on the front. These new routers will be replacing the 4400 Series. This is primarily a hardware upgrade that will improve performance making things bigger, better, faster. WAN acceleration is no longer required to reach top speeds of 500-600Mbps and the USB ports are 2.0. The 4500 Series routers will be available at the end of February.