grepWin is a search and replace tool that can use regular expressions. This allows you to preform powerful search and replace functions with a simple intuitive user interface.

grepWin adds context menu to the Windows Explorer shell easily search selected folders.

Once started, grepWin allows you to customize the search or replace in many ways: File sizes, file types, Case Sensitive, Include/exclude system folders, etc...

it also has a create backup function which can be VERY handy with bulk renaming.

Since regular expressions can sometimes get complicated, grepWin allows you to add your most used expressions to a presets list.