I'm working on a IDE+debugger+circuit_simulator, developed in C++ Qt4 framework.
It can edit/highlight/compile/debug/simulate: gcbasic, pic-asm and avr-asm files, still very basic.
Needs Qt >=4.6.2, Gpsim and Gputils instaled.
Simavr, Gcbasic and Avra are included in the project.
Only tested in Linux Ubuntu 10.04, but i think it could run in windows with the win versions of Gpsim, Gputils, Avra, and compiling Simavr for win.
If someone wants to test it, there is a projet in sourceforge: http://sourceforge.net/projects/simulide/