Just got my X51V in today and when I put in a 1 GB sd card, I cant download onto, I can read files off of it, but not download programs to it. And when I check the available memory, it says 497MB, when my computer shows 999MB...any ideas whats going on?

just a hunch ... check the tab on the side of the card to see if it's in LOCK position ( read only)

BTW ... your post said you can read files off from it ...that means you do have some files on it ... how did you manage to get it on in the past ??? ... and how can your PC read 999MB when it already hold some files ???

its unlocked, I added a small file, few KB, to try it. deleted it and now I can't write anything to it with the computer either, and it shows 499M MB now.....this is a new sd card, is it just bad?

try reformatting it & start over ... that should give you 1 GB ( although the actual indication varies depends on brands) ... I have 2 (1Gb) cards, when fresh formated .. 1 says 997MB.... the other says 999MB ... nothing dramatic like in your case where 1/2 of it is in LALA land

This is a known problem. Search the forums and you'll see a lot of people have had the same problem with WM5.

Will updating the rom fix the problem? I still have the first one. Just got a new sd card and same thing...was not the sd card....