just beware that the nano-itx enclosure will only fit nano-itx sized boards-- in many cases, there is a very limited market for these. they have started offering a mini-itx case--basically, they added a adapter ring that extended the depth of the case a couple of inches..
but neither are a really perfect solution. i know for sure that to fit a mini-itx board in your dash, you need a minimum of 12" of clearance in the dash-- i don't believe the s-10 has this(i put a radio in a 01 s-10 a while back-- i believe the dash is only 7-10" deep).. but that doesn't account for wire management, so it gets really cramped really quick..
the best bet is to look at nivanov's build thread(here)-- he used a variation of a nano-itx board. and then hopefully you can get a better idea of what is involved with that installation route, and if it is the best method for you.