Join Date: May 2003
Location: Ohio's Cycling Capital, America's North Coast.
Unless I'm reading your question incorrectly, you would be better served buying a used or low end mountain bike rather than getting new rims ($$) for your hybrid. Even a cheap set of 700c wheels and tires/tubes will run you at least $150.00 Not to mention the compatibility issues that can arise between the two cassettes (your rear cogs and chain wear together, mixing components of varied condition often leads to poor performance).
I have a trek 730 w/ 700c and was not comfortable on the trail. Packed limestone was fine, but dirt, mud, and sand require a wide tire and small rims (26").