There's a lot of marketing hype out there about TRANSFER RATES.
However the thing that most of the time limits disk access speed is arm
movement and rotational delay. Only after these two things have taken
place with the actual data transfer take place. The limited exception
to this is when the data is in the relatively small cache. A 16 meg
cache might sound big to some, but compared to a TERABYTE, it's a drop
in the bucket, so in most cases you're stuck with seek time and
rotational delay being the critical factors. And when these two things
have gotten you to the right spot on the disk, you've still got to
transfer the data into memory, which again is limited by the rotational
speed of the disk (usually 7200 RPM). So yes the TRANSFER RATE with
eSATA can be faster than USB, but the disk doesn't spin any faster
regardless, nor does the access arm (seeking) move any faster.
Now regarding NTFS, once you get above about 8 gig, using FAT32
becomes incredibly ineffecient, wasting more and more space because
"cluster" size increases until it can waste a ton of disk space to store
small amounts of stuff.
Finally partitioning. It does NOT speed things up. In fact if you
frequently access stuff across multiple partitions, you've got to move
the access arm further, slowing everything down. The main advantage to
partitioning is separation of things like software and data. This is
particularly convenient for things like backup/restore and reorgs. If
you keep all your software on C: and your data on say E:, then you can
backup your C: and reorg it relatively infrequently, since it doesn't
change as fast as your data. And when you back up or reorg your data,
you don't have to do it to your C: partition. It's very convenient, and
the backups and reorgs go faster (a tradeoff with the increased seek
time if you have to move between C: and E: frequently).
Clear as mud? Welcome to disk management! :-)