I'd get a new xbox 360 (with wi-fi built in)... it has the best netflix app (don't know about the ps3 or apple tv) of any streaming device i've used. For reference, i've used a roku, pc, cheap-***** walmart RCA device, and a built-in TV app... all are below the quality you get on the 360.
The nice thing about the 360 version of netflix is that it is almost always updated to keep it performing well. The other aps i've tried start off quick, but anytime netflix makes a change, the other devices seem to get slower. With microsoft's push for digital content apps on the xbox, you can guarantee the netflix app will be well supported into the future (i would assume the ps3 would be the same way).
The nice thing about the 360 version of netflix is that it is almost always updated to keep it performing well. The other aps i've tried start off quick, but anytime netflix makes a change, the other devices seem to get slower. With microsoft's push for digital content apps on the xbox, you can guarantee the netflix app will be well supported into the future (i would assume the ps3 would be the same way).