I’ve found this little neat string that can be used in the VS.NET integrated Find and gives your current project / solution / file total line count:
^~(:Wh@//.+)~(:Wh@\{:Wh@)~(:Wh@\}:Wh@)~(:Wh@/#).+
To use it, just press CTRL+SHIFT+F, then select Use Regular Expressions and finally write the file extensions in which you want to count the lines of code. 
The results will be displayed at the Find result window’s end.
Thanks go to Germán Schuager for the tip.
