<qa>  How many sites will participate in the trial?This pragmatic trial is a 2X2 open randomized study of patients in advanced HIV disease who have failed on conventional Highly Active Antiretroviral Therapy HAART regimens including all three classes of anti-HIV drugs. The first randomization will allocate patients to an intended 3-month antiretroviral drug-free period ARDFP or No ARDFP. The second randomization will allocate patients to Mega-ART 5 drugs or to Standard-ART up to 4 drugs. The total study duration is 6.5 years with 5 years of intake and 1.5 year minimum of follow-up; median duration of patient follow-up is about 4 years. The target sample size is 390 patients and will provide 75 power to detect a 30 reduction in the hazard rate for the primary endpoint with mega-ART. Sixty-four sites will be participating in the trial--24 VA, 19 UK and 21 Canada. 