Assembly language

Ok, starting on the level. I'm a newbie at programming. I used to learn Visual Basic (shit sucks I know, please don't kill me it was school mandatory), very little C# on my own, but then I dropped programming but installing Linux has rekindled my love of programming and I'm currently diddling with Python and C.

I do how ever want to learn assembly, or at least try it out but I read something about there being a lot of different types of assembly languages.

Fuck? As if assembly isn't hard enough already. so /g/, I assume there are some people here who know a shit load about this, what's the best place to start?

If you're going for nerd cred and e-penis then go for MMIX and complete the exercises in Knuth. If you don't have enough cred to know what I'm referring to when I say Knuth, then FUCK YOU.