I admit ignorance to the compatibility. I think udma can be used on non-udma devices, it just can't utilize the extra speed. Do you plan on upgrading your body at any time? If you find out it's backwards compatible then it may be worth getting a udma card if you know your next body would be udma compatible.
Lexar is also good, so I've read. But I've been a SanDisk guy for as long as I can recall. Just got a 16gb. So I'm rocking that with an additional 8gb card.
What are the speeds? I can't imagine at the price difference the Lexar is the same. Get the fastest one your camera can handle. Especially if you're shooting RAW.
edit: There's a video from Lexar demonstrating the importance/significance of different speeds. This guy shows the amount of time it takes to write a sequence of shots that fills the camera buffer. There's a big difference between a 5 second delay and 45 second delay.