www.irfanview.com is the address you need. Irfanview is a super-fast and simple freeware image viewer and editor which supports all major graphic formats.
We looked at the site at the start of 2008, but there have been some good additions to the software since.
As well as the simple and quick editing features, you can download the add-on pack with some free extras as long as it is for non-commercial use.
These include direct FTP, e-mail tagging from the thumbnail viewer, running slide shows and doing batch conversions.