You might also want to look at p4merge from Perforce (http://www.perforce.com/p...e/downloads/ntx86_64.html
). It's in the P4V installer. Note that you don't have install any of the other Perforce stuff if you're not interested in the version control - p4merge works fine stand-alone. There's no cost - Perforce only charges for user licenses for use of their server-based software (and even then a limited license for up to 2 users is free).
Another contender is TortoiseMerge, an open source comparison utility bundled with TortoiseSVN (http://tortoisesvn.tigris.org/TortoiseMerge.html
). Again, you don't need to use or install Subversion to use the TortoiseMerge tool.
I use Beyond Compare for folder diffs or diffing files from explorer, but I use p4merge for diffing from my development tools (only because I'm too lazy to reconfig them to use BC2)