C: 144
=

    i,o,c,l;main(int n,char**v){for(n=atoi(v[1]),i=3,l=2,o=0;o<n;i++){for(c=2;c<=i-1&&i%c;c++);l=c==i?(o+=(i==l+2),i):l;}printf("%d, %d\n",l-2,l);}

Takes N (>=1) from the first command line argument, hope that's okay.

Sample run:

    $ for i in $(seq 1 10); do ./twinprimes $i; done
    3, 5
    5, 7
    11, 13
    17, 19
    29, 31
    41, 43
    59, 61
    71, 73
    101, 103
    107, 109