Tango music is a completely different ball of wax. OK, let me give you an easy one to start with. There is a little snare roll on the 1 of every measure in this tango song. From there, it's just a matter of counting the rest. (edit: the snare roll actually ends on 1. It doesn't start on 1. Just thought I'd mention that so you didn't get confused.)
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The problem is that not every tango song has a nice backbeat to help you out. But, this song is a good place for you to start with the counting. If you have trouble finding the 1 in this song, you're really gonna cry when a song without drums comes up.
Start with the first one. Once you get the hang of it, see if you can pick up the 1 in these songs.
[youtube]km6aN4PSa_c[/youtube]
So snare roll is that drum "rattle"?
With your classic tango beat, it's going to want to count it like 1. 2. And-threee-four. 1. 2. And-threee-four. The "and three-four" could sneak up on you if you count it that way and you'll be late, then have to rush to catch up. Get used to thinking through the whole thing as 1-and-2-and-3-and-4-and-1... Having that in your head will help keep you in time. You basically double the tempo in your mind and then the fast steps are not so fast. Once you get used to that it'll flow a lot easier.
You could try to get a metronome (there are phone apps, or a cheap ones at music shops). Pick a tempo and set it to play eighth notes. A smarter metronome will distinguish the 1 from the others, and the up beats from everything else. Eventually you'll start hearing it in every rhythmic sound you hear. Then you'll find yourself making up rhythms to normal sounds like your footsteps.
Whats a good tempo? I downloaded Mobile Metronome for Android. It has Time Signature # (note measure)/# (Quarter note or Eighth note)
and beat subdivision (as quarter note, eight note, triplet, sixteenth). Not sure what all those settings mean.

If you are trying to keep the beat then imo you are doing it wrong. Feel the music, feel your partner and glide. The beat is there just for the music and your steps do not have to be on beat.
I have one year of argentine tango under my belt and I am no expert.
Houston we have a problem.

Haven't touched Argentine, just American for now.
Found this on youtube. Whats the verdict, are they following it?
I think I can count at the beginning (them moving to it helps), but then I get lost in the middle. Seems like it stops following slow, slow, fast, fast, slow. Around 1:20 mark.
[youtube]CFiq-2LAQpY[/youtube]
Of course you need to be able to dance to the beat. All great dancers feel and understand the rhythms that they are moving too. However, as a dancer, the "musical/rhythmic beat" is really not as paramount to good dancing as much as feeling and understanding the PULSE of the music/rhythm being played. A song can have many rhythms being played simultaneously, but the PULSE of the piece will remain the same. That is what you need to feel/understand fundamentally.
I guess that most of my experience was with competitive ballroom.