The old version of rdesktop 1.3 in the stable feed for pdaXrom 1.05 seems to work fine for me on RC5. It reset my XP host a couple of times when I first connected, but once I quit running three monitors it connected easily. The only issue I'm seeing is keymapping for xmonobut. Using the Mail button to serve as the right click works in every other application I've tried, but not rdesktop.
Generally, I'm finding that a lot of the previous console apps and simpler X apps work in RC5 without recompiling.