Vista Disk
As a Windows Vista user, you will now and then come into a situation when something does not work right. All of a sudden the system does not boot, or there are strange errors. Too many people just panic in such situations and end up simply reinstalling the whole system, or switch to Windows 7, without even trying to repair the problem.
Indeed taking care of a Vista system that has stopped booting properly can be quite difficult, since Vista itself does not offer too many built-in recovery tools (although it does have some, see windows recovery console or Booting In Safe Mode for a few examples of using them). If you have an OEM Vista, like most people these days, it is likely that you don't even have an original Windows bootable CD which you could use to try and repair your installation.
As a precaution - or even after things go bad, if you have another PC with net access - it is a good idea to create yourself your own Vista boot disk. There are various ways to do that, but the one which is probably easiest and fastest for most people is to use the Spotmau PowerSuite universal Windows boot CD:

Spotmau PowerSuite 2009
If you can't afford that (or feel like you are up to the task) you can also try and use the built-in Vista recovery:

Choose Startup Repair Options
See also: