Maybe i can throw in some field experiences here:
The Acer seems nice, i also use an Acer netbook on my own. It still runs very well after 2 and a half years, works quite fast with any pdf-reading, text editing, coding, browsing web and data, etc.. Also still runs multimedia quite well, diashows, movies up to 1080p, even renders .mp4 movies in 1080p (All processes closed, two extra fans against overheating, ram at 100% load, but it renders).
In the beginning it would even run Battlefield 2 on full (netbook!). Not any more, but really suffices for college work.
Acers however tend to overheat after like a half or one year, they need to be opened and blown through regularly. No big deal, and they are pretty good besides that. Parts have a good compatibility, and can be easily exchanged or upgraded if needed. (Not the graphics card and processor sadly, but the other parts)
Speaking of reliability, i don't quite remember how often my Acer fell off the desk, also i once tripped on an icey stairway and fell right on it. It still works.
I would definitely recommend using an multicore (are there still single core processors anyway?), and everything with over 2.0GHz usually handles everything ever needed. To be honest, the last 1.6GHz single core i had in hands ran windows 8 very well and fast, but you see the difference once you open more than 5-6 browser tabs.
Furthermore, most of the professors here use either Macs, or they use Thinkpads. I don't really like Thinkpads, neither Lenovo, some of the older Lenovo modells i saw had much oem software installed, that used to slow them down pretty good. However thinkpads suffice for working, but i still wouldn't await any high definition multimedia results with them.
I neither know about the Asus nor the Toshiba, so no info on that.
Solid state drives - i'm still sceptic to those, but a fellow tried it out, and he said they'd really make a noticable difference in speed, so it might be an idea to run the system on those and still pack the data safe on the normal HDs (at least i would do so)