For creating (and learning) regular expressions I find The Regulator to be a great help. The tool itself is free but it does have some rough edges:

• It doesn't work when running as non-admin; this can be overcome by starting it with Run As, but this seems a bit much for the task that it is supposed to perform.
  
• Today I ran into a different problem: for some reason it threw a System.TypeInitializationException when I tried to start it. After a quick google I found an entry that suggested reinstalling the entire thing. This also seemed a bit much; because there hadn't major changes to the configuration of my machine, I tried a more deductive approach: something had to have changed since I last ran it. The only files in the folder that had changed were the config-files. After removing the config-files, it automagically started working again.

Don't be fooled into thinking The Regulator isn't worth the effort: I've found it to be a valuable tool in developing and learning about regex. I especially like the interactive manor in which you can create an expression and test it. If you haven't used it, you should give it a try.