Picasa is photo viewing and editing software, it also have uploading photos features that is good. Picasa developed by Google Inc. Everyone known that what is Google. Thats why only it is popular. I think it is made by google only for photo viewing. Because it havent there many features for picture editing.
There have simple features for editing like Crop, Rotate, Brightness, Red Eye Correction and some simple features. So we cannot said that it is also photo editing software. I have using Adobe Photoshop CS4 for photo editing and I have use windows photo viewer for viewing photo in my PC Windows 7 64 bit.
If I have to install a software for editing so why I use Picasa. I am not recommending this software.