Basically these are just PC manufacturers and the Steam Machines are just PCs. So for them its more or less business as usual, and many of them (like Alienware)

Basically these are just PC manufacturers and the Steam Machines are just PCs. So for them its more or less business as usual, and many of them (like Alienware) already had quite similar systems on sale. With the possibility of the Steam Machine brand resulting in more sales for products they would be selling in a similar form anyway, it was an easy sell i guess. It could potentially be a huge business to sell the best steam machines on the market.