Dude!
I own BOTH cards he/she's talking about and going from a GF2mx to a GF4mx DOES MAKE A HUGE DIFFERENCE! Is it a GF4ti no, but that doesn't mean he shouldn't even consider a GF4mx, he/she can get a GF4mx for half the price of a GF4ti 4200.
I went from playing Counterstrike at barely 99fps dropping all the way to 30-40fps pretty much when ANYTHING action oriented happend; to now playing at 99-100fps pretty much ALL THE TIME only dropping to never less the 60-70fps and that's for usually a second or two!
I hate to just come out and say you're wrong but... YOU'RE WRONG! If he/she doesn't have over 100bux to spend like alot of younger students can't then the GF4mx is a great buy... Take it from me I OWN BOTH FRIGGIN CARDS!
Should he/she just wait until the GeForce5's come out and get a GF4ti then, that's their call. But Octupus trust me if you want a very good/quick fix to your GF2 situation, take it from someone who was in your shoes, get a GF4mx now and save up for a GeForce5 later...
--btw-- my system specs are a P3 1GIG with 512SDRAM, so even with my beast of a system it made a BIG BIG BIG differnce in pretty much every game I own... But hey if you got extra cash to burn, then I would say sure get a GF4ti that's a no brainer; but I doubt you would've even considerd a GF4mx if you had enough cash for a TI, right?