Has anyone tried the Lazarus IDE? http://www.lazarus-ide.org/
I miss the ease of being able to mash up a quick windows GUI prototype in Delphi, and just wonder if having this IDE might be worth the clutter of yet another compiler on my computer.
Yes. Very convenient for writing GUI apps. Lazarus/FPC has the bonus that you can compile on multiple OSes with the same code (more or less).
There are some differences in the language. FPC's Object Pascal is the most correct variant, but it also accepts Delphi variations. The only major difference that may cause grief is that generics are implemented differently than Embarcadero's XE versions. (IMHO, FPC's OP is more correct.)