my knowledge of C is poor
Here is a good starting point. Work on your C language then you can migrate from assembly to C in no time.
Browse through Raisonance site, you should get a wealth of information there.
I finished a small assembly program for a factory, I replaced a PLC with a microcontroller and the program worked great but it was pain programming it in assembly and it took me 1 day to do and debug in simulator but I'm completely satisfied with it.
Now I will redo the program in C (which should take me 15 minutes) and compare the generated assembly code with the original assembly code I wrote and let you know.
I used PIC16F84 for that project but I'm planing on using 8052 for my next project.
Regards
Mahmood