The GeForce 2MX is a substantially faster card for 3d. The RV100 chipset in the Radeon 7000 is *incredibly* stripped down compared to the "real" Radeon R100/R150 among other things missing hardware T&L entirely. The GeForce 2MX is also stripped down, with only half the pixel pipelines of the "real" GeForce2, but it still has twice as many as the RV100 and retains T&L support. However, the 2MX did come in varying RAM bus configurations, and a really bottom-of-the-barrel card with 32-bit wide SDR might just manage be worse than a "decent" RV100.

As has been noted, both are "budget" cards. Sawtooth G4s usually shipped with Rage 128-based cards and a 7000 is barely faster than that (At least the PCI 7000 in my B&W G4 benchmarks only about 20-30% faster than the stock 128 at Quake timedemos) but it does at least minimally support Quartz Extreme. (Basically it's the same card that shipped in the second-gen 600/700Mhz white iBooks.) The 2MX if it's good one should put you in the same ballpark as the Radeon that was an option for DA G4s, or, of course, match the 2MX that was an option for the Cube. It's totally a personal decision whether a video performance upgrade equal to the difference you'd get from buying a January 2001 machine vs. a July 2000 vintage one is worth the effort of flashing it.