As I wait for my RaspPi to arrive, I've been reading more about Arduino. It looks rather interesting, and until recently - I didn't even know there was "open source hardware". (ok, clearly I've spent too much time in the software world). 

I'll plan to initially spend time seeing if I can get my Raspi to talk with a pile of opto22 devices that I have. That hardware use RS-485, so I bought this inexpensive USB to RS-485 adapter on amazon.com (one of the answered questions specifically noted this device works with the RasPi, I hope I can get it to work, too!)

When reading about the SD cards to use, apparently there was a problem in the past getting the UHS cards to work. It seems those issues have been resolved as noted on the elinux.org RPi SD cards site. For my RasPi, I ordered the SanDisk Ultra 8 GB SDHC Class 10 Flash Memory Card 30MB/s SDSDU-008G-U46 for less than $9, also from Amazon. (note the RPi specs say that no more than 20MB/s should be expected, so no sense in spending a ton of money on ultra-speed card). There's more performance information on the SD Card Benchmarks here.