No way. You're forgetting about one crucial element -- profit! Even with the cheapest parts, a $199 computer leaves very little room for profit. A $599 PC, even with the Micro$oft license (which Dell and HP pay very low rates for), they are still making a decent margin.
At $199, they may sell a lot of them, but without a healthy profit margin, they won't be in business very long. Then who do you call when the "no name" parts start to fail?