Thanks for that.
If you find there are no log files created in the \xampp\apache\logs directory then you may be missing the runtime file (Microsoft Visual C++ 2008 SP1 Redistributable Package (x86)) as XAMPP for Windows 1.7.7 is compiled using VC9 as opposed to older versions that used VC6 to compile Apache.
Certainly Windows XP and Windows Server 2003 may well not have this runtime file and so would need it to be installed so Apache can start.