Seeing since I make a living working on computers, I finally decided to take the plunge and upgrade my four year old computer to Vista Ultimate just a cople days a go, so I can get familiar with it. My computer has Pentium4 2.8, 1.5GB RAM, 256MB geforce 6200 video.
I was expecting a nightmare after everything I have read, but Vista has been running great for me. I installed all my drivers without a hitch, I only have one software program that won't run, but it is minor and inexpensive software to upgrade.
Overall, I am very pleased, Vista will take some geting used to and has a few annoyances (like constantly asking me to allow programs to run or be installed) But it is actually running faster than my previously installed Windows XP Pro.
I might suggest that when installing drivers, DO NOT install the drivers from Windows update, I have seen this cause problems since Windows 98. Go to the manufacturer website and get the latest Vista certified drivers and hide the drivers on the windows update page so you don't do them accidentaly. Also, the 64 bit version of Vista is much more picky about drivers, so make sure you can get drivers before installing this. Another thing I think you should NEVER do is an upgrade install, always do a clean install. I cringe at the thought of performing an upgrade install, have seen this crash many many computers from Windows 95-98 days to today.