Jarir bookstore is at the following places:

Qatar Showroom: Salwa Road, Ramada Crossing, Doha
Showroom Timings: Sat-Thu 9am-10pm; Fri 4pm-10pm
Tel. No. +974 444-0212, Fax No.+974 444-0432

Al Rayyan Showroom:Al Sheikh Salman bin Khalid Al Thani Center, Al Rayyan Al Jadeed Road, Doha
Showroom Timings: Sat-Thu 9am-1pm, 4pm-10pm; Fri 4pm-10pm
Tel. No. +974 411-4322, Fax No.+974 411-4838

I've found most of the new books over here..

There's also ISpy book shop at City Centre, but less variety of titles.

I have heard about the Virgin Megastore as well, but to be honest I don't know the location.

Hope it helps!