And the X700 XT isn't that great.. I can turn on all options with my GeForce FX5900 XT, though it gets laggy. I don't know if it gets laggy with the 9800 XT, since the X700 XT performs quite similiar to it.
my 9800 XT performs flawless but that is mainly cause of the rest of my comp!
my roommate got a 9800 pro and he can hardly play U2 for the reason that he lacks ram memory! if you got 256 MB and a good card... it isn't enough!
You will be able to play with all eye-candy turned on with the x700 but not the 5700 LE I'm afraid (mainly the full AA/AF will most probabaly make the LE laggy). And as everyone else is saying, the bottleneck will just rise to the proc. or your ram so your full spec is important.