Homebrew PCBs

Ok, all this talk has given me the bug to build a milling machine 
for pc boards. Something that will be semi-precision.
Maybe some of you guys can offer some good tips for building an X/Y 
table?
I am a poor person and want to hold cost down as much as possible, 
so ideas like the "Drawer Slide" linear motion bearings are greatly 
appreciated!

Slides:
I'm not sure how much play are in those drawer bearings. Probably a 
lot. I'll have to look for some good ones, or maybe make my own 
slides from brass or UHMW channels. I've dealt with different types 
of gibs and round shaft/ball bushings before, so can probably figure 
out something that is semi-precision at low-cost.

Linear Motion drives:
Stepper motors are the obvious low-cost solution, but I'll need to 
find some good resources for cheap parts that will work properly as 
a complete system.
True servos? Better but not as available as "surplus" ?
Either one would of course need suitable controllers and software.
I can write some software (VB and Perl) but I think some 
shareware/freeware is available to handle conversion from different 
CAD programs...
Then I'll need to fabricate the mechanical drive portions: Leadscrew 
or Timing Belt like printers?

Design parameters:
What are the largest boards I should allow for in the x and y axis 
travel? 8", 12"?

Anyone who has experience with such things, please chime in if you 
know of some good sources for info or parts!