If you buy the adaptor you could go several ways. HDMI cables have to male ends, so if you get a female HDMI adaptor then you need the cable as well. If you get a male end HDMI cadaptor you can just plug it into your ps3. DVI is also a male to male cable normally, so with a female to female you would need botht he HDMI and DVI cables to hook it up. If you get a one side male then you could plug it into your monitor or ps3(depending on which end is male), and then you would only need one cable to connect to the female end.
Alternatively you can just get a DVI male to HDMI male cable, and then you wont need to use an adaptor.