I was under the impression that a USB connected disk might perform
poorly compared to a CF card.

I have a 200 gig ATA133 disk in a cheapie USB 2.0 enclosure attached
to my Mobilepro 800. I also have a 64 meg CF card (rather old, about 2
years or so I suppose) in the same machine that I use to boot the
NetBSD kernel.

I formatted a NetBSD ffs partition on the CF card, and the USB disk is
acting as root.

Write performance on the USB attached disk seems way better:

USB disk:
10485760 bytes transferred in 2.242 secs (4676966 bytes/sec)

CF card:
10485760 bytes transferred in 5.086 secs (2061690 bytes/sec)

This is the command I used:
dd if=/dev/zero of=junkfile bs=1024k count=10

Can I expect slower performance if/when I buy a microdrive and plug it
in the CF slot? Maybe I'd be better off putting it in a PCMCIA adapter
and putting a CF ethernet card on it? Or maybe I just hook the
microdrive to a USB card reader?

I have a solid state USB 256 meg pen drive that I use which seems
quite a bit slower than the disk.

Andy