I tried out Steam a while back when I subscribed to Cedega, and it worked pretty well then, but that was before HL2.

I was worried that I would lose much of the DX9-specific stuff the Source engine offers, but I think most of it is covered by the Cedega specific code - it’d be interesting to see how much better (if any) Cedega renders DoD… I may well resubsribe to Cedega yet!