.NET Regular Expression

In the past, I wrote a Regex blog for beginners: http://hi.baidu.com/feishunji/blog/item/2fe96c63a11109610d33fa73.html.
It introduces a small regex test tool: Regex Tester.
But today I got an article introduce another: http://www.codeproject.com/KB/dotnet/regextutorial.aspx, the tool is called Expresso.
Expresso looks more powerful while Regex Tester is more agile.
Get your preference and happy coding~ :)