Terry,
If the plotter is old (circa '92 or less) there is a chance that you will not be able to get the proper drivers to run with the latest version of AutoCAD or AutoCAD LT. I can't speak to other computer drafting software platforms as I only have used AutoCAD extensively. Until recently I was using a Houston Instruments pen plotter (very similar to the pencil plotter probably) and ran it using AutoCAD version 14. Version 2000 and on would not support it and HI is no longer, so updated drivers were out of the question.
If you decide to go for it the most important thing you can do is make sure you have the right cable (if it serial connected). I had a cable for mine that was supposed to be the correct one. I tried for months to run the thing and pulled out most of my hair doing so. Finally I decided to buy a new cord (the old one had been checked out by a local computer technician as correct and working). Once the new cable was in place it worked flawlessly on the first try. So that made me wary of serial cables.
I would say go for it if you have a Mac platform program that will run it. If you have to go through the expense of a non Mac PC and AutoCAD software forget it. I have used some smaller shareware drafting programs that were very confusing. AutoCAD is great but it does have a learning curve. Not only that but they always seem to find the need to tweak the plotting in every new release trying to make it easier for the casual user. In doing so they confuse the hell out of us who know the program and use it often. So what I am saying is you may get a PC and AutoCAD only to find out that plotting is not straight forward. A new version of AutoCAD is $2,800 and I have seen old versions selling on e-Bay for as little as $400. AutoCAD LT is around $600 and would work fine (basically a stripped version of full AutoCAD--no 3D and not AutoLisp support). If you are only going to use the 2D option a cheap computer will run it just fine. I run AutoCAD versions 14, 2000 and 2002 at work on Duron 800 chips and that is plenty. I ran 12 and 14 for a couple of years on a 386 and 486 machine when I first started my business. It wasn't screaming but I ran a business with it.
Also if the plotter is like my old one it is a one sheet clamp/plot scenario. Mine did not have a roll option. Mainly this is because the pen plotters jump around and plot in what it considers the most efficient manner. This more or less throws using a roll out the window since the plotter could want to take in paper from either side while plotting and could prove disastrous if you are the only one tending it and trying to keep large sheets in shape for it to feed back and forth. My new plotter spits out just like a desk jet printer. I used it to plot the panels on my S&G.

Overall I'd say it's probably not worth the trouble. You could simply use your Mac and drafting software for it to draft your work and then find someone to plot it out. Plenty of places for that around. Hope this helps.

Later,

Tony

: I've got an opportunity to get one of these. It.s not being used due to a
: replacement lazer type. The price is right So , Being technically
: challenged I'd like to know if having a plotter could be much help drawing
: out plans?
: I have a Mac , so do I need a PC that will run an Auto-Cad program in
: conjunction with the plotter?? Or should I stay clear of things I know
: nothing about??
: Thanks for any response.
: Terry