Well, ATi cards used to have very superior 2D quality than the Nvidia cards, but the GF4 cards seem to have inproved it greatly, till there is almost no differnce. I've heard people say the the Ti4200's 2D quality isn't as good as the Ti4400 or Ti4600's though.
The ATi card overclocks better than the GF4 ti 4200. Just make sure it's retail, made by ATi. Or you can get the one at newegg for $99. It's oem but it has 3.3ns memory, basically the same as retail but underclocked (you can download powerstrip and set the clock at 270/270 or 300/300 to overclock). And a subsequent GF4 ti4200 costs around $170.
The ATi card has more efficient anisotropic filtering. The nvidia cards take a huge performance hit when you turn on anisotropic filtering, so I see the ATi card as having the advantage. The ATi card has better image quality with anisotropic filtering+FSAA turned on whereas the nvidia quincunx tends to blur things a bit. The ATi driver issues have just about disappeared so that's no problem. Even if there was no "ooo cool $99 dollar deal" at newegg I'd still recommend ATi because I value image quality more than pure speed and it overclocks better so it balances out.
That is severely flawed. That Radeon 8500LE OEM is actually a OEM R8500. As for the 3.3ns RAM, probably just a freak accident. Usually the R8500LE OEM has 4ns RAM and the R8500 has either 3.6ns or 3.3ns. The Ti4200 overclocks quite well, as I've seen Ti4200 128MB go in excess of 570MHz RAM and 300MHz core. At those speeds they get close to Ti4600 speeds, which is definitely not bad at all.