The quality of the PS2-dvd is very good, with the monstercables and a good TV the picture is great.
I have a friend that have a Pionner 737 dvd player for about 1000£, I could not see any difference in picturequality, the 737 is faster in therms of accessing the dvd menues a.s.o.
But picture, no way, you would need a very very expensive TV to see any difference at all.