I prefer you get the r29147 instead of an older beta.
The 32bit version of dd-wrt even though its the latest version do not work with these realtek cards.
There is also Intel ones too that work on both 32bit and 64 bit I did have 4 intel cards that looked the same but 2 of them did not work in dd-wrt but all 4 were fine in M0nOwall. I also had issues with the watchdog feature that would reset the cards every so often. Which is built into the driver software giving me issues in the Intel based cards.
These are the cards here I used on both 32 and 64bit.