Irfanview is quite the capable little program. You can view tiff files along with jpeg, gif, png, and most of the other image formats. It will let you convert photos from one format to another. You can create new scans directly from your scanner. Jpg files can be rotated without loss of quality. Irfanview can create thumbnails and contact sheet overview images.
Download at www.irfanview.com for free. You will have to pick from one of the several websites hosting the download.
To install, be sure to pay attention to the options as you go. Irfanview will default to installing a toolbar for your browser. I always opt out of those browser extras. It is not related to Irfanview other than they get paid to offer the option. And since it is default to opt-in, most people install the stuff.
Browser toolbars offer limited benefit. I think they slow your browsing speed, and reduce the size of the viewable portion of your screen. I have heard of people having 10 different toolbars at once. It is a tax on the software novice. If Irfanview wasn’t so good, I wouldn’t suggest it on this basis alone.
Here is a collection of Irfanview tutorials: