I purchased a FW800 enclosure for my Seagate 500GB 5400rpm HD. I just got a 2010 13" MBP. I was previously using a 2006 MBP with an ExpressCard slot, and had this hard drive connected over eSATA. According to TomsHardware the max sustained write speed of this drive is around 65MB/s, which is what I was getting over eSATA. So I got the FW800 enclosure now that I can't use eSATA with the thought that I'd be getting the same 65MB/s that this drive is capable of. FW800 should be able to handle up to 100MB/s. But I'm only getting around 40MB/s, closer to what I should be getting if I was using FW400. Any ideas about why I lost 25MB/s in transfer speed?