I've found an example here but that only centers one column and I can't really adapt it to my needs. What I'd like is something like this:

I've found an example here but that only centers one column and I can't really adapt it to my needs. What I'd like is something like this:

Try this:
\begin{tabular}{|m{3.5em}|b{1em}|b{1em}|b{1em}|}
\hline
%% row 1
&x1
&x2
&x3
\\\hline
%% row 2
Long Label
&1
&0
&1
\\\hline
%% row 3
Long Label
&1
&0
&1
\\\hline
\end{tabular}
For more info on table formatting see http://en.wikibooks.org/wiki/LaTeX/Tables
EDIT: changed c to b{}