I confess I don't know if MSPaint will open TIFF images, but if it does, could you then use the Save As option to save as JPEG?
If not, try IrfanView, a free image editor/converter, or Graphic Workshop, which isn't free.
A while back I scanned most of my slides and put them on an external hard drive. The problem is that to preserve as much information as possible I scanned them with as much resolution as possible figuring I could always downgrade but wouldn't be able to upgrade. In addition the files are tiff. files and I find that in order to use the images on a digital photo frame the files have to be jpeg. The files are about 64mb large and a ***** to work with because of their size. My question is, are there any programs that will convert from tiff. to jpeg. I have PhotoShop Elements 4 and I haven't found anywhere that tells me how to convert the files. Guess I should have scanned them as jpeg to start with but it's too late now. I have two laptops one with XP and the other with Vista. Both with a 2mhz processor and 2 gig memory and 160gig hard drive.