How much does the extra frame of input lag matter?

Hello. I used to play SF4 on the PC and played older fighting games on snes/ps/ps2 before that, and I would like to buy a console to play SSF4. This is not an XBOX vs PS3 thread, even if that is the decision I am trying to make, but rather a question to people who would know more about this than me.

Overall, I prefer the PS3 because one of the only three games I am interested in whatsoever(Demon’s Soul; I guess I miss the days when games were unforgiving) is an exclusive, while the other(FF13) runs way better on PS3. However, when it comes to SSF4, I have heard that it has 5 frames of input lag, whereas the XBOX only has 4. Since SF has 1 frame combo’s, this sounds significant to me, but then again it might not matter much, and just be a matter of what you are used to. Any input(!) on this would be appreciated.

In addition, if anyone could shed some light on the online service quality that would be great. This forum seems to have a bunch of threads with complaints about it, while the XBOX forum on the contrary seems to be all sunshine.