Westover is mostly McKinley and not subject to the boundary change. Some of the area is Tuckahoe (although I think that's actually Highland Park) and some of Tara-Leeway is changing from Tuckahoe to Nottingham and Glebe to McKinley. This map is pretty easy to read:

http://www.apsva.us/cms/lib2/VA01000586/Centricity/Domain/110/Supt%20Recommendation%20-%20Variation%20B_Street%20Map.pdf

OP, it isn't necessarily by neighborhood, since planning units aren't the same thing as neighborhoods. Most that I know of contain at least two planning units, and sometimes may feed to different elementary schools. The true Westover area feeds to McKinley but around the margins to the west and north are units that feed to Tuckahoe and/or Nottingham.

There is map on the Arlington website that you can blow up. Alternatively I think you can type in a particular address and it will list the planning unit. Layer in the Planning Area and zoom in and it will show you planning units and tell you the schools they are zoned for.. http://gis.arlingtonva.us/gallery/map.html?webmap=efd4da094f7841d0bff522d037697bd9

This map shows where the boundaries will be starting in 2015 down to the street level. http://www.apsva.us/cms/lib2/VA01000586/Centricity/Domain/110/Supt%20Recommendation%20-%20Variation%20B_Street%20Map.pdf

for OP, it'll be Lee hwy

I'm having a really hard time envisioning the boundaries because the only map I have is tiny and it identifies communities by their zoning unit number, which means nothing to me! Is there some rough shorthand out there of the major roads that will capture the new boundary? Or is there at least a map out there that zooms in enough to show the names of streets etc.?

yes, fall 2015.

I don't think westover is in bound for the new school.

We may be in the market to buy a house soon, and we like the area near Westover. I'm pretty sure the boundaries for the new elementary school cut into some of those neighborhoods. We're generally happy with whatever school we end up with - all North Arlington schools seem to be really great - but we'd prefer to start at the same school we end up at. Will kids be attending the new elementary as soon as the 2015-2016 year?