As the forum module is in tabular formate, is it possible to make it
A table (in this particular case) is more accessible to blind users than a collection of DIVs. The forum module listings *are* actually tabular data - a grid of titles, owners, number of replies, and timestamps. Tabular data that, when moved to CSS, would lose a lot of its charm.
You should look into the table CAPTION and TBODY elements.