The speed is also different, of ram that is. 222MHz (444MHz DDR) on the 128Mb and 250MHz (500MHz DDR) on the 64Mb.
This means that the cheaper 64Mb card can outperform the 128Mb on certain games and systems, obviously games which prefer memory bandwidth.
However, if you are planning on buying one, which I assume you are, or have, because why else would you ask, and you really want a Ti4200 then get the 128Mb, because the new generation of games will need the memory.
Oh, and you can get a stable OC to just under Ti4600 speeds.
But the big cards of last year were not the GeForce 4's, though that's what I have. If you have the money get a Radeon 9500Pro, or if you
really have the money get a Radeon 9700pro.
That's the lesson over for today.
That's probably, no no, definately the most sensible thing I've ever posted.
The guy probably won't even come back to this thread now, lol.
Baz