Don't have much of a problem with the PS3 online. Admittedley it does not have the functions of Live to a degree with in game messaging and stuff which are due shortly in a future firmware update and it does not cost anything.
What the PS3 is missing is the online platform maker which is home that it how games are meant to be networked with the PSN.
Most of the games with issues are from lazy devs who make the game on the 360 and then port it across to the PS3. Both system are designed differently and they do not work well on the PS3 because of this. COD4, Burnout, Ratchet and Clank, RFOM, GT 5 Prolouge work with out framerate issues as they were coded for the PS3.
The PS3 can stream stuff from your PC with Media servers including Media Player 11 and since the PS3 have like the 360 allowed Divx files/codec to be played on the them.
Beforehand Linux awas a good bet due to the fact you could put players on Linux area that the PS3 would not have recognised and played Divx movies on it.