Al and the two "Rider"s have good points. I'll just add that it should be fairly simple to swap out your current 13-34 7-speed cassette for a 7-speed cassette with a different assortment of gears. See Sheldon: http://www.sheldonbrown.com/k7.html#7cassettes
Presumably, you've got a code K cassette, and are finding the 29-to-24 transition too big. Switching to a "G" would compress the low (easy) end a bit. An "F" would compress both high and low ends a bit, and a "Megarange" would actually expand your high end and even out the spacing over the entire range.