Any external drive you buy will include a HDD from one of the major manufacturers. Lacie does indeed have a good rep, mostly from the Mac zealots, but they are simply "just another reseller." Most external HDDs use the same USB and SATA/IDE chips as well. My suggestion is to check out a few head-to-head reviews and pick a solid performer at a good price. I personally just by bare hard drives and external drive enclosures. 5 minutes of assembly will give you 500GB of external drive for well under $200.
BTW, to clear something up: You can buy/build a USB or Firewire drive that has an internal SATA connector to the hard drive that is then converted to USB/Firewire (being that all of these are serial connections the conversion is simple and results in relatively low lag. This is a benefit over external drives that are IDE (parallel) native and must be converted from a parallel connection to serial). An external SATA drive is known as E-SATA, and the connection is pass-through with no conversion.
