Hi. I know someone who uses a laptop for his cnc control so you may be ok if you turn off power save etc.but an old pc is better if you are running Xp,Windows 7 using the parallel cable. Ethernet breakout boards are outside your price band. As to which machine,big question. For fine detail you need good signals,and that means Ethernet smooth stepper boards which would give you better cutting detail on Smaller items like your pens.but Ethernet boards cost a lot more and in some cases also need a breakout board also.you will need the software motors etc. Your best bet is to look on eBay for a up and running machine with cnc etc. Two sieg sx2 cnc mini mills have been sold on eBay this past week for sub 600 pounds.