Negative PCR DNA test mean anything?

I hear alot of bashing about PCR DNA test for HIV.   But if you test negative for the PCR DNA test, is that conclusive?  And realistically speaking, how long after possible exposure is a negative PCR DNA test conclusive?   And if this test is conclusive with a negative result sooner than the HIV AB test is conclusive with a negative result, why do some claim it isn't as useful a tool as the HIV AB test?

[sunsarethebest]

Im not sure but i beleieve that even with those types of tests they still need to be confirmed with an antibody test. Pluse those types of tests gives a lot of false positives from what i hear. So the choice is yours.

[allthesigns]

PCR tests give false positives but rarely false negatives assuming enough time has elapsed (28 days).  Most doctors would still recommend an antibody test at 3 months after exposure just to be certain.  

[concerned20072007]

I have heard that PCR DNA can give false positives but is there any evidence about how often they give false negatives?   I had a PCR DNA test at 17 days after exposure and it was negative.   If I took it again and was negative at 28 days, is that pretty certain I'm in the clear from HIV?