What programming languages have you used in the past? My only programming was in BASIC and Assembly on 8-bit computers, which I stopped when I moved up to a 286 Windows machine. A few weeks ago, I started up with the ATtiny13. Don't know much about 'C', BASIC is considerably different (what happened to line numbers?), so went with Assembly. The instructions are very similar, but still have a few things to learn about labels and a few assembler things that are new to me.
If you have no programming experience... Guessing you would be better off learning 'C' or BASIC, as these are what I see most in web projects. The compiler libraries contain routines that handle setting up registers, PWM, ADC, keypads, LCD desplays, and much more. With Assembly, you will need to cut and paste routines into your program, or write your own.