Advantages of External HD vs Enclosure?

Though it's been a while, last I checked a USB enclosure + HD were cheaper than an external HD of the same size.

Any advantage of one over the other?

I've found it comes down to portability. My Lacie 160GB external HD, I've had for over a year now and it's still going strong. I carry it around with me a lot. It's reading and writing speed is about the same as a standard ATA133 IDE 5400RPM drive.

I have a few friends who use external enclosures with Western Digital and Maxtor hard drives and they have both failed once within the last year and they don't carry theirs around nearly as much as I do mine.

I use a firewire drive and they both have USB2.0 drives. Technically speaking, firewire has a lower peak transfer rate than USB2.0 which is what I find most funny. Mind you, if I'm not mistaken, a HD doesn't even come close to maxing out the transfer rate of either specification.