Are you looking forward to install windows Vista ?

If your answer is yes , pls consider these things in mind:
1. HCL (Hardware Compatibility List) is an extensive list of computers and peripheral hardware that  have been tested with the windows Vista OS.
2. BIOS: Before installing win-vista on your pc , you should verify that your pc has the most current version of  BIOS. Especially important if your BIOS does not include support for advanced configuration and power interface (ACPI) Functionality Vista required this functionality to run smoothly.
3. Driver Requirements : To suceessfully install windows vista  , you must have the critical drivers (Device) for your pc like hard disk device driver.However Win-Vista Comes with loads of drivers but if your device
driver is not in Vista OS , check device manufacterer website.Win-Vista will not recognized devices that dont have windows vista drivers.

CLEAN INSTALL/UPGRADE: once you satisfy that your hardware meets all the requirements , you need to decide  whether you want to do an upgrade or a clean install.
An upgrade allows you to retain your old OS settings/applications and files.If you have a pc running win-2000 pro you have to choose clean install.

LIST OF OS's ALLOW IN-PLACE UPGRADE:
----> If you are running win-xp pro.
----> you want to retain your old operating system .
----> Want to preserve any local users and groups created on current OS.

Win-2000 :  HOME BASIC (NO) PREMIUM (NO) BUISNESS (NO) ULTIMATE(NO).
Win-xp :      HOME/PREMIUM/BUISNESS/ULTIMATE (YES).
Win-xp media center : HOME(NO)/PREMIUM(YES)/BUISNESS(NO)/ULTIMATE(YES).
Win-xp tablet pc : HOME/PREMIUM(NO)/BUISNESS/ULTIMATE(YES).
Win-xp Pro x64 :  HOME/PREMIUM/BUISNESS/ULTIMATE(NO).