The best is yet to come
Derek, congratulations on your results. OTOH, sharp is in the eye of the beholder and the differences you will see in prints made from your slide with more capable scanners will amaze you even more than your initial results.
For exhibition quality from 35mm you should scan with either a high end scanner or a film scanner such as the Nikon 9000. Even then, you are pushing the realm of the possible when you think about printing larger than 11x14 ... that is if you are going to print for the normal viewer who, rather than standing at 'normalviewing distance' insists on moving up and sticking his/her nose into the print. This is not meant to denigrate your initial results at all .... just to point out how much better you can do in the future.