I've been building something similar for a while - I bought 3 easydrivers from sparkfun several years ago, intending to build a mini cnc, never got them to work right, got an arduino for my birthday and finally got them working, that was april! Since then I've found at least 3 ways to burn out an easydriver, and come to the realisation that after a 12 hour day at work is not the best time to play with electronics.
I had 2 steppers with spools lifting and raising weights on strings and had just been trying to work out how to do the software when I found this site a couple of weeks back. have installed your embedded/server combo, and now have a working machine!
I had to make a couple of changes to the embedded code to make it work with the easydrivers, taking out the Motor1 and Motor2 code and just using the AccelStepper calls:

AccelStepper accelA(1,5,4);
AccelStepper accelB(1,9,8);

I also had an intial issue with having the coils reversed vs what was expected, so when the controller told it to go down it went up, right left etc. swapping coils a & b on the easydriver fixed that. I now have a working system, although its still needs mounting on a decent sized board.
Mechanically rather than putting the motors out on the corners I've put both in the center to simplify cabling, then I'm running the strings out via hooks on the corners of the board and down to the penholder. it literally is string a the minute, need to get hold of something better at some point, but for now have settled for tesco value string on some cobbled together spools. (my kittens loving the rest of the ball of string! shes also pretty keen on the machine when its running!)

https://picasaweb.google.com/lh/photo/6U5Vs3cPjP_sH3WTbtMzLg?feat=directlink

Got the bot mounted on a proper board now (2 quid offcut from B&Q, result!)
Set it going doing a drawing to show my mum it while she was paying a visit today, seems to work ok, although one of the motors is skipping steps, think I need to play with the current regulator on its easy driver.

https://picasaweb.google.com/lh/photo/nACDed9enZIgJYu-taC_uGQf8X_k_vYw-yk271_kNbE?feat=directlink

just need to write some code to convert svg to bot commands now...

Yeah, seen the kritzler bot, that was the code I was looking at using before I stumbled on yours, could get it on the arduino ok, never got it to actually do anything though, may have to have another play, as he already has the vector stuff, may end up creating a frankenstien of the two 😀

Still getting a drawing that gets narrower as it gos down the page, need to work out whats doing that.

So after 2 years of it sitting looking sad in a corner (and then hiding it in the shed for a bit out of pure shame) I've finally found some time to play with my bot again. Had left it with a dud sketch on it, and the laptop that I was using before is no longer functional, so started afresh with the latest version. Couldnt get the a1 software to upload to my uno (think it needs a bootloader update, but couldnt work out how to do that) so I bought a sainsmart mega 2560 off amazon and have swapped that out so I can use the mega server. Is working now, but for some reason the vertical axis is flipped. The x axis is correct, but the vertical is inverted. Kinda expected both to be wrong if it was a wiring issue, anyone got any ideas, as I'm a bit stumped?
server is as per the 1.7-1.6 zip on the github, am running the precompiled controller from the same.

Thankyou! Had not paid enough attention when I modified the config to work with the easydrivers rather than the adafruit board, and had motors A&B swapped from before (I'd even put the correct defs in the post above so I wouldnt lose them - doh!) also seemed to have re-spooled the string at some point, and hadnt respooled them the right way round. is all going in the right directions now. Amazing how much easier this is when you can play with it during the little ones afternoon nap rather than late at night when hes asleep and everything else is done.