For most applications, using a multi-tasking environment is like shooting down a fly with a rocket, especially on an 8-bit microcontroller: you will get your target, but it's far from elegant. I would say that if you can't figure out how to get your software running on a device wihtout using multi-tasking support, you either lack sufficient insight in the process you are about to confront or you just have to choose a controller with more capabilities and/or a higher processing speed.