I get different numbers than both of you.
Here's google calculator to show my work and so others can easily play with the numbers.
5.6042967 grams of 11b and p to generate 100 megawatt hours of energy. Of course this assumed that every atom of boron and every proton fused. I have no idea what the real ratios are, but if someone wants to plug them in there just multiply the 11b mass with the number of boron atoms it takes to generate a fusion on average, and also multiply the proton mass with the number of protons it takes.
Spelled out a little, here's what I did.
((100 megawatt hour) / (8 * (10^6) ev)) * ((11.00900 amu) + (1.00727638 amu))
100 megawatt hour / 8 MeV = 2.80867939 * 10^23 (note the units cancel out so the number is unitless).
So 2.80867939 * 10^23 is the number of fusions needed to create 100 megawatt hours of energy.
2.80867939 * 10^23 * ((11.009 amu) + (1.00727638 amu)) = 3.37498678 * 10^24 amu
11.009 amu is the mass of 11b (from memory)
1.00727638 amu is the mass of a proton (from wikipedia)
3.37498678 * 10^24 amu = 5.6042967 grams
It'd be fun and amusing if a few other people tried it out, too, to see how many different answers we can get for what should be a straight-forward calculation.