dear brother u hv ample tym to prepare for css as u r going to appear in 2012(bshrt-ezindgi o sehat, Inshallah)... so don't get confused over books. go with tariq awan's book as i hv seen it n found it very useful n detailed book on indo pak history. and if u want to consult more than one book, as is mostly recommended by the seniors, do prepare iswari parsad. decision is always urs others can only suggest
be blessed