[ltp] Thinkpad model differences

[Tom Hoover]

I've been running Debian on a Toshiba Tecra 720CDT (133 mHz) for a
couple of years.  Although I'm satisfied with the performance (X runs
fine, as long as I'm running a light window manager, like icewm), I want
to upgrade to a machine with DVD and USB.  I've heard great things about
the Thinkpads and Linux, but I'm having a tough time figuring out which
model to buy.  I've searched using Google, and visited many different
pages, but I can't find a source that _simply_ describes the features of
each different model.  IBM's site doesn't help, as I'm not interested in
a new machine (I don't need that much speed, and I'd rather not spend
that much $$$). 

Can someone help by pointing me to a site where I can compare the
features of older Thinkpads?

FYI- the features that I'm looking for are:

MUST HAVE:
DVD (preferably internal, but might consider external)
USB port (one is fine)
PCMCIA (one is fine)

Nice to have:
500 mHz or faster
Light weight / thin (almost anything would be thinner and lighter than my old Tecra)
3 hr battery life (so I can watch a complete movie without plugging in)
External floppy (to help keep weight down)

I don't need a high performance machine, as my main use of the laptop is
reading email and web surfing.  If I need to compile a program while
using the laptop, I just ssh into my desktop machine and do the "heavy"
work there.  The DVD will allow me to watch movies while traveling, and
the USB port will allow me to plug in my USB thumbdrive.