Electronic Workbench is pretty good for designing analog and digital circuits. However its a bit expensive if you plan on buying it and the demo version wont allow you to save your design.
There is also Microcap 7 from spectrum-soft that auto generates passive/active filters by just specifying...
You can use any of the micros from above without purchasing the whole board kit by only buying the programming module of the micro. Its just that when you have the kit its a lot and fun easyer to discover all the possibilitys of your micro before going into a more complex application.
You can...
If you want a good introduction to microcontrollers you can use the AVR ATmega163 from ATMEL with the STK-500 card kit that comes with a C compiler called AVR studio that is very friendly user.
Specs of the microcontroller:
CMOS 8 bit RISC
130 instructions
32 8 bit registers
16K flash memory...
