is kingston class4 is okay for TX1?
The bit-rate of the TX1 HD video is about 4.4 MB per second. A Class 4 card is rated to deliver at least 4 MB per second. You can imagine that some Class 4 cards might be adequate and some might stall after recording for awhile. I think the best and least expensive solution would be to go with SanDisk Ultra II SD or SDHC cards, which have a write speed of 9 MB per second. They would also be better for Burst or Continuous Recording than a Class 4 card. For the next few days, CC has a special on 2-GB SanDisk Ultra II SD cards, for $25. They would give you the astounding amount of 7.5 minutes of HD video recording! Spend more and get a 4-GB or the soon to be available, 8-GB Ultra II SDHC card and record HD video for 15 or 30 minutes, respectively.