Is it possible to read or write Bengali on these operating systems?

Since these Windows editions don’t have support for Unicode, you won’t be able to use Avro with them. However, there are some primitive ASCII based softwares that will let you do so, but that you can use only for printing purposes in your own computer. Not for sharing anything on the web i.e. chatting, mailing or designing webpages.

However, you will still be able to view Bangla websites if you have Microsoft Layer for Unicode installed. If you have MS Office or latest version of IE already installed then Microsoft Layer for Unicode is already installed on your computer and you will be able to view Bangla websites.