Yes there are many programs that will do this. Many scanners have a resident program that does this for you. How you save your slides is important as well.
I agree with Bob, you need a scanner, or some way of getting the image off/from the slide, into the computer. Does your projector have an output for this?
I would think that even connecting a projector to the computer, via a capture device can be arranged. Something like Avid or Pinnacle can grab single feeds from your source.
Be sure to have the highest capture that you can, so you can enjoy the full resolution of the images. 300x300 is fine if you aren't looking for crisp pictures (or only have a mediocre monitor to view them on). Much will depend on what you're gong to do with the images once they are converted.
I've never once felt I had too much resolution on a conversion, but have wished some that I've seen were (way) higher.
If you're ever going to print them seriously, you'll want them as either RAW or Tiff.
I hope this tips help you, & you have some great images.