Combinations into an Array?

Using vb.net, I'd like to create an array of all possible combinations of a set of X objects from a master set of Y objects.

i.e. If Y = {1 2 3 4 5 6 7} and the sub set limit is 2 then a partial list of combinations would be {1 2}, {1 3} {1 4}...but {4 1} would NOT be in the subset because {1 4} and {4 1} are different permutations but NOT different combinations.

I don't want the permutations, only the combinations.

Thanks!

Someone just asked this same question:

http://forums.devshed.com/t74853/s.html

so did someone else:
http://forums.devshed.com/t70346/s.html

i attach a vb.net project with the above - it might be some help