About how many margaritas would it take to surpass the drinking limit in my state of .08%?

After I finished my answer, I found out that there are some resources on the internet to make this calculation.

I tried this calculator, which gives results for Margaritas:
http://www.ladrunkdrivinglawyer.com/bac_calculator.html

For a 80 kg man taking 1 Margarita, over a period of 1 hour, the result is .008 g/210 liters of breath, so you could be convicted of driving while intoxicated in most states.
I do not think that the calculation is valid, in this case. I prefer my answer:
http://www.answerbag.com/a_view/1111896

Anyway, you could also use one of these "BAC calculators" to get an idea. (Blood-Alcohol Content Calculator):
www.rupissed.com/
http://www.dot.wisconsin.gov/safety/motorist/drunkdriving/calculator.htm
http://www.1800duilaws.com/forms/bac.asp
www.beertown.org/education/calc/bac/bac.aspx

1) You can eat many of them and you are not going to have any problems:
http://en.wikipedia.org/wiki/Pizza_Margherita

2) "IBA specified ingredients for margarita:
- 3.5cl (seven parts) tequila
- 2.0cl (four parts) Cointreau or Triple Sec
- 1.5cl (three parts) lemon or lime juice "
Outside from this 7:4:3 ratio, there are also other ratios, for instance 3:1:1 (3.6cl; 1.2cl; 1.2cl)
http://en.wikipedia.org/wiki/Margarita

3) "Tequila is most often made at a 38% - 40% alcohol content (76 - 80 proof), but there are also several varieties of Tequila produced with 43% - 46% alcohol content (86 - 92 proof)"
http://en.wikipedia.org/wiki/Tequila
"With a 40% alcohol content, Cointreau is strong for a triple sec (usually 23% alcohol content)."
http://en.wikipedia.org/wiki/Cointreau

Ratio 7:4:3:
- the least alcohol content would be:
(3.5 cl x 38 %) + (2.0 cl x 23 %) = 1.79 cl
- the greatest alcohol content would be:
(3.5 cl x 46 %) + (2.0 cl x 40 %) = 2.41 cl

Ratio 3:1:1
- the least alcohol content would be:
(3.6 cl x 38 %) + (1.2 cl x 23 %) = 1.64 cl
- the greatest alcohol content would be:
(3.6 cl x 46 %) + (1.2 cl x 40 %) = 2.14 cl

4) According to Widmark's formula:
c= A / (m x r)
c: alcohol concentration in blood
A: mass of alcohol taken
m: mass of person
r: factor for body distribution (0.7 for men, 0.6 for women)
Notice that:
- we must take into account also alcohol's density, ρ ≈ 0.8 kg/l = 0.8 g/ml
- 1 cl = 10 ml
- the result must be multplied by 1.000 to get a promille concentration
Source for Widmark's formula:
http://www.icadts.org/t2004/pdfs/O22.pdf

5) Results:
For 2.41 cl alcohol taken from a 80 kg man:
c= (2.41 x 10 x 0.8) / (80.000 x 0.6) x 1000 = 0.402 promille
For 2.41 cl alcohol taken from a 50 kg woman:
c= (2.41 x 10 x 0.8) / (50.000 x 0.7) x 1000 = 0.551 promille
So, if your state limit is 0.08 % (0.8 promille):
- a man over 80 kg could take eventually two of them if they are not from the strong kind
- as a woman, you should weight even more than that to take this risk. Better you stay by one.
(I suppose you do not drink also any other alcohol, such as beer)

6) However,the real value of the concentration could be between 10 and 30 % less, because some of the alcohol will immediately leave the body (kidneys, lungs).
And the concentration goes about between 0,1‰ and 0,2‰ down per hour.
This would leave:
- the 80 kg man with 0.36 promille
- the 50 kg woman with 0.50 promille (still too much for two margaritas)

I depend only one your body weight and your metabolism rate.Some can drink many more drinks then others and still rate low.

IF you make them with one shot of tequila, probably two margaritas in an hour would put you over, depending on your body weight.