The 5200 runs half-life2 - it may run it slowly, thats beside the point - if you want performance, buy a more expensive card, not a value/entry level card.
I believe it was mentioned that the 5200's will be running hl2 on a dx8 path. As will the 5600. The 5900 will be running it with _pp.
How is a card that devs are defaulting to a dx8 path affecting the coding for dx9?