Vista requires a lot of horsepower, which I detail below. Most XP machines will require new hardware-$200 – $300 worth. If your machine is more than a couple years old, that could be just the beginning. People with old machines are typically better off to buy new.
Also, upgrading an operating system can be tricky for the casual user. It may well cause headaches. Nonetheless, I’m sure many people won’t heed this advice. So, I’ll tell you how you can minimize installation problems.

You’re probably going to need additional RAM. Microsoft recommends 512 MB for the most basic version of Vista. For premium versions, it recommends 1 GB. I would double these numbers. Microsoft recommends 128MB of RAM for video. Again, to be safe, I would double that. To make sure your computer is up to snuff, visit Microsoft’s Vista upgrade site. If your computer gets a green light, you can proceed.

First, back up everything on your computer. Making a checklist is advisable. Remember your e-mail, photos, data and Internet Bookmarks/Favorites. Make sure you know all your passwords. Back up program settings if possible. I recommend using an external hard drive. You can do an in-place upgrade over most versions of XP. The sole exception is the 64-bit version of XP. Practically no one has that. Theoretically, Vista will keep all your files, settings, and programs as they were in XP. I haven’t tried this, so I can’t say how well it will work.

I wouldn’t count on an in-place upgrade to go smoothly. Things could go wrong. Set aside plenty of time. To learn about in-place upgrades, visit Microsoft’s site.

Your alternative to an in-place upgrade is a clean installation. (recommended).If you buy a new machine with Vista installed, you’ll still need to transfer your data. You can use Microsoft’s Easy Transfer to move files and settings from your XP machine. That included a special USB cable. It generally does a good job of transferring settings and files, with the exception of Firefox data.
Once Vista is running, you should install security software. Both AVG and avast! antivirus programs will run on Vista. They’re free. Windows Defender, the anti-spyware program is included with Vista. Microsoft also offers their own antivirus program called Windows Live One Care.

For a more detailed article on upgrading to Windows Vista visit Extreme