If I remember, you are also in Greece, right? I have the Plaisio-branded Classmate 9" tablet and I DO NOT recommend it for reading. The screen is too bright and it runs very hot, it is heavy (comparitively) and the battery is not the longer-lasting one (about 2 hours).
If you do not want to wait till the end of the year, perhaps the new Smart Q7 model is OK for now. Since you would order it from China, being in Greece is not so much of a disadvantage compared to everywhere else. It is Linux, but I recall posts saying that windows CE is being ported. Check out this thread:
Another thought: I think the "Public" bookstores also carries the Archos line of PMPs - but I don't know if the new 7" is available yet.
The Asus line should have a tablet available (hopefully in Greece too) by the end of the year. Otherwise, why not go for a good general PC that can run all of the software you are interested in trying for now (like a 9" or 10" Acer or Eee) and then trade up when the new wave of eink-type tablets come along?
My husband uses an "old" 15" laptop to read PDFs, annotate, bookmark, browsing, etc and is just fine with this until large-screen newer tablet technology comes along. Not very portable, but he does these studies at home.
"Set priorities and compromise on the rest" is the operative phrase!