On our network we have several Dell GX 280 XP SP2 Pro pcs and several Dell GX 270 W2K SP4 Pro machines. They all have 512MB memory. The XP machines have 3.2 GHz Intel processors, the 2K machines have 2.8 GHz processors. They have pretty much the same software load. The hard drives (40GB) are about 25%-35% full. The testmy speed for XPs on our 6Mbps connection is consistently close to 6Mbps, but the 2K machines are consistently 2.0-2.5 Mbps. Running testmy test on the 2K machines running in Safe Mode with Networking gives results around 4.0-4.5 Mbps. Any idea why this difference?