When in Windows.
Two graphics programs i couldn’t live without when stuck using a Windows machine (as i am everyday at work) and, if i’m totally honest, wish existed for the Mac…
IrfanView by Irfan Skiljan
Paint.NET by Rick Brewster/dotPDN LLC
Both free, both lightweight and both, as i said, indespensible if you have any image manipulation to do. Irfanview i use primarily for saving screen-grabs but it also has a great batch conversion tool. Paint.NET is like MSPaint’s bigger, cooler brother. When you don’t have access to Photoshop (or can’t wait for it to load) then Paint.NET is an excellent quick and simple alternative.
While i’m on the topic of free software, i’ll also quickly mention NCH Software. They write lots of applications. Some commerical, some freely available… but from what i’ve used so far, all good. VideoPad, which recently helped me out of a spot, is a nice little video editor and one of the few free ones to be found on the web. The other prog that i’ve found really handy to have about is Switch - i recently used the new Mac version of this to convert some music from WMA to a more iTunes-friendly MP3 (since MacOSX iTunes won’t do the conversion, even though Windows iTunes will).