Hi,
There is a specific way of doing this. However, it uses gpedit.msc,  which is not included with Vista Home Premium. I have included a link to  a hack by me on how to get it to work under Vista Home Premium. 
THIS  IS UNSUPPORTED BY MICROSOFT! Use the manual install Beta 1.1 at the  bottom of the page, not version 1.0. 
http://www.vistax64.com/tutorials/265870-gpedit-msc-all-editions-vista.html
Once gpedit.msc has been installed: Open the "
Computer Configuration"  hive. Now open "Windows Settings" then "
Security Settings". Open  up "
Account Policies", and then single click on "
Account  Lockout Policy". You should now see three settings in the right hand  pane.
-  "Account lockout threshold" is the number of failed  login attempts before system lockout. 0 is the default. You must  specify this value first.
 
 
-  "Account lockout  duration" is time before computer unlocks itself. 30 minutes  is the default if lockout is enabled. 0 is never unlock until an  administrator unlocks the computer.
 
 
-  "Reset account  lockout counter after" is the time before invalid attemps returns  to 0. If you have lockout after 3, and 2 failed attemps, after this  time, invalid attemps will return to 0. 30 minutes is the default  if lockout is enabled.
 
 
Double click on a setting to change it, and once you have double clicked  on a setting, click the "
Explain" tab for more details.
Hope this helps,
Richard
P.S: I think that richc46's link will only work for systems on a domain, but I may be wrong.