Yeah, you're good with the hard drive!
The processor on the 1000, 1000BK, and 2500 are all the same Renesas SH7727, which operate at 100 or 160mhz. That amounts to an old Intel Pentium1 processor, basically. I'm willing to bet that it's running at 100mhz, since 160 mhz would be the speed if it's overclocked. As far as I know, the MPC1000 isn't overclocked.
Here's some info on the processor...
http://www.renesas.com/fmwk.jsp?cnt=sh7727_root.jsp&fp=/products/mpumcu/usb_device/sh_usb_family/sh7727_group/
Read up on it and also read the Specs link. You'll see that it has alot of capabilities. But to ask any more questions of it wouldn't yield any more answers here, to be honest with you. We're hoping that JJ would study the specs entirely, so that he could take more advantage of it if possible (but somehow doubtable).
http://www7a.biglobe.ne.jp/~mpc1000/
I highly recommend trying out version 3.06 (which is free).
Read up on the site about that and the NEW OS 4.xx for more info, and also visit the JJ OS forum...
http://www.mpc-forums.com/viewforum.php?f=25&sid=817d26d9ded718f1c2ccd58caaa75373