Hi Petunia,
A neuropsych is much more able than a regular psych to do detailed testing work that differentiates one diagnosis from another. They specialize in diagnosis, not treatment.
You might find information about where to locate a tester at the "Help and services" links on the left side of this page (searchable by state):
http://www.aspergersyndrome.org/Home.aspxIn addition to IQ and achievement testing, I would want to make sure the tester would do most or all of the tests listed here, or their equivalents. I draw this list from the things the tester did with my DS when he was dxed with Asperger's (autism spectrum disorder) at age 5.
Children's Memory Scale (memory)
VMI-V (visual-motor integration)
NEPSY Social Perception (social awareness/understanding)
ADOS (autism diagnostic observation schedule)
Vineland (adaptive behavior - parent report)
PDDBI (ASD characteristics - parent report)
CBCL/TRF (general behavior - parent/teacher report)
PLSI (pragmatic language - teacher report)
Hope that helps,
DeeDee