Yup, but there's no need to get a GF4MX420
DDR as it's 64bit DDR which is only as fast as 128bit SDR! If gaming was a concern then you should find a Rad8500LE hardly costs much more and is a world apart in 3D. In any case, if you go Radeon watch out for non-ATI Radeons as they often skimp on things which can effect image quality and dual display as well as 3D perf.
The GF4MX cards do have DVD decoding hw, the Radeons are perhaps a TINY bit better for DVD playback but you are talking tiny diffs, since the Rad7000 is cheaper that would make it a better buy. In any case if your CPU is faster than 600mhz then hw decoding is pretty pointless anyway. The only gfx cards which really enhance the DVD playback (or any video) are the Rad9000, Rad9000pro and Rad9700 which all use DX8 hw functions to enhance the video and reduce MPEG artifacts. Rad9000 are pretty cheap but still very new, in a few weeks prices should drop a bit further. I haven't had this all confirmed by independent reviews yet though, but it is official stuff.