The added speed will likely not affect its performance in your axim dramatically - unless you do things like vermontcathy, which require lots of reading at a time.
I haven't played DVD rips on my axim, but I have the played [high quality] anime fansubs I watch in my desktop with my 4GB CF II card (it's a Hitachi Microdrive). Each of these episodes is about 160MB per 20 minutes, so it's pretty heavy duty stuff, and I've only had problems because: 1) My axim got really hot, so the processor slowed down considerably so it caused skipping, video and audio out of sync, & buffer underruns. This was after 3 or 4 hours watching anime, though; 2) Before I upgraded to the latest Betaplayer release. So
you should have no trouble with regular DVD viewing using a "regular" card, if you encode good sized files and have a nice sized buffer (there are threads on how to do this elsewhere).
HOWEVER, if you're planning on adding/deleting big files, like movies,
_constantly_ then you might want to get the faster card because it'll save you time in the long run.
My 4GB Microdrive works fine for my needs. It ranked in the middle of the pack with a bunch of other cards in a digital camera review at about 4MBs, although it's supposed to be able to reach up to 7MBs (according to Hitachi). I don't know how that ranks in flash memory speed (as in 40x, etc.?), but I find it works slower than burning a CD at 8x or 6x (in CD-R writing speed).
That works fine for me since I use most of the space for mp3s, which I won't change often. It takes about 20 minutes to transfer 1GB from my computer to my microdrive (through a card reader), so that is a bit slow, but I transfer much less than 1GB on a regular basis. You just have to think about how you're going to use it and whether you really need the speed for yourself, as a matter of convenience, because your axim will be fine with a standard card - you don't
need the extra speed, it's just convenient (unless you actually need it for some time-sensitive application or something...)
Uhm, I think I kinda went off on a rant/tangent near the end, but I hope it helps,
-D
