I saw a couple of people build a DS3L with OCZ Reaper modules so I guess it would be safe. You have 2 choices depending on how much you want to pay: CAS5 for 61$ after MIR or CAS4 for 96$ after MIR (heard this one might overclock better)
Motherboard manufacturers don't seem to keep up with memory at all, but you rarely hear of incompatibilities any more. I just buy memory and assume it will work. My friends and I usually buy Patriot memory due to price/performance. Right now I'm running a 2x2GB DDR2-800 kit that's really solid. They always seem to have good rebate deals on newegg, but you do have to save the rebate immediately because they cycle them every two weeks and you can't find them when you need to send it off.