For theory part of all group 1 subjects, stick to institute modules, they are nicely explained in a simple manner. Regarding practical problems:
Accounts-Hanif & Mukherjee or PC Tulsian
Law ethics and communication - Inst. module
Costing- P C Tulsian
FM - PC Tulsian
Taxation - Singhania.
For all theory parts, I advbise you to study the theory content given only in Inst. module. In addition, one must refer d suggested answer of previous papers and RTP, MTPs etc contained in ICAI website for download. As you are giving your attempt in may 2011, there is ample time to prepare a good schedule and to score more marks if u stick to your prepared timetable. All the best.