There is an issue with XAMPP 1.7 with PDO. If you try to use something that requires it like Magneto this will become painfully relevant with Apache crashing miserably. The fix is to replace the libmysql.dll file in both the apache\bin and \php folders.
You can see the English repost here.
In a nutshell:
-Stop Apache & MySQL
-Download pgp 5.x win
-extract the new libmysql.dll
-copy it to apache\bin and \php and allow it to overwright
-restart Apache & MySQL
-Success.