If you had to spend let's say between $500. and $600.for a good new desktop (pc),which one would you buy? It seems that,for the same criterias, HP is $100 more expensive than Compaq, is it worth it?

HP and Compaq are one company... I find it hard to think that the exact same units with identical equipment would be $100 more than the other... Not good business....
Was one unit on sale ? I recently brought a new Compaq for about a hundred less of a HP because it was a closeout on a spacific model...If thats the case, by all means buy the lesser priced one... Just check and compare the two models side by side for equipment...

HP and COMPAQ are combine together in PC market, it's named HP COMPAQ.
But in Notebook Computer, I like the HP prefer.