I have the exact same problem also running 32-bit vista.
Idle worked the first time I started it but after that it doesn't start.
I did run the command and got this error.
C:\Users\Joakim>"C:\Python25\python.exe" "C:\Python25\Lib\idle.py"
C:\Python25\python.exe: can't open file 'C:\Python25\Lib\idle.py':
[Errno 2] No such file or directory
I also not able to start the interpreter from cmd using the python
command. I've looked around a bit and read something about adding to
PATH. Haven't tried that because the guide wasn't written for Vista.