Determine if Cozaar (losartan potassium), an angiotensin-II receptor antagonist, given in a single daily dose is as effective in the treatment of essential hypertension as Avapro (irbesartan), also an angiotensin-II receptor antagonist. Losartan is comparable to irbesartan with respect to patient quality of life including overall health perception, well-being, social functioning, sleep disturbances, sexual functioning and cognitive functioning.