I built myself a budget box, and now I'm gonna build one for my father.  I wanna upgrade so I intend to give him my budget components and buy beast-type stuff...will I be able to just throw my current hard drives on the new mobo and start the array; granted I put them in the same order of course? 

yes

Pretty much yes.

The difficulty would depend on what version of unraid you have.

before you tear down the old system, make sure you what drive is your parity drive. this is more important for 4.x then 5.x. (on 4.x you should take a screen shot of your drive array page with all of the drive assignments)

run a parity check before teardown just so you know the data is good.

 

on the new system,

when you start it, do not format any drives if it asks you to. something is wrong. seek help.

if it comes up as it should, run another parity check with -nocorrect. to make sure all is good.

 

it should be pretty simple to upgrade.