I'm looking at purchasing the following display: http://uk.rs-online.com/web/p/lcd-displays-alphanumeric/5326824/
It's 20x4 and driven by a KS0066U, which appears to be pin for pin compatible with the HD44780.
I think I'm fairly confident it should be OK, but I've already been bitten by buying a display with limited capability once (6100 knock-off on the breakout board - I can only get one library to work, and full screen updates take a good 5-10 seconds!).
Thanks in advance,
Mike.