Questions about gameplay on ps3

[ElectricShock]

Ok i have a xbox 360 & just got into ps3 i purchased one last week

i rented a couple games
uncharted---great game
ratchet and clank--great game
motorstorm i own and its very cool i love it

Well now to the questions

i rented nba live 08....madden 08.
i have played the xbox 360 versions of these games
both of them had very weird lag issues and this is offline not online
And on nba live 08 there was jagged lines everywhere
I read the reviews for madden 08 on ps3 and xbox 360 and its the same game but ign gave ps3 version 7 and xbox version 8
i dont get it???

And i was considering getting guitar hero 3...i played it on xbox 360 and loved it

But i read in some forums that gh3 also lags....

i want to stop buying so many games for 360 and start my collection of blu rays and games for ps3 since its on my living room tv now

But whats up with the lag issues on the versions for ps3 and none on xbox 360...

And will this be fixed with madden 09 and games down the road
And whats the deal with gh3 also.

Thanks...Just questions from a new concerned ps3 owner.