Hello,
(ANS) I am a computer veteran with many years experience of running windows (literally every version of windows Microsoft have created from Dos through to Vista).
No.1 Officially Microsoft say you can upgrade from XP to Vista but from past experience I sincerely definitely DON'T recommend this approach as its fraught with a disaster waiting to happen. Its NOT a method I would use myself ever.
No.2 Please NOTE that I have myself installed Windows Vista on a top specification workstation that runs windows XP SP3 perfectly (a DELL Workstation Precision 330) Vista runs dog slow on perfectly sound XP hardware. So my advise is DON'T install Vista on XP level hardware. You will only be extremely disappointed by the end results.
No.3 There is no doubt that you can only run Vista on the latest hardware, that is hardware that is specifically designed to run Vista. I have a second DELL system purchased only a couple of months back (DELL Studio 540) I have Vista Home Premium SP1 and even though its configured & tuned to run Vista its still slower than XP, I have both machines running side by side and its clear that XP is the faster & more responsive in sheer performance.
No.4 If you really must have Vista then you only really have x2 realistic options a) Buy a new machine with Vista pre-installed or b) buy a system & vista DVD and perform a clean fresh install.
No.5 In terms of the "timing of a purchase" now is an incredibly good time to buy a new PC or Laptop if you have the funds available. Because prices are at rock bottom & computer stores are totally desperate for retail sales. You wont see computer prices as low as this for a very long time in my opinion. They can only go back up.
**Windows Vista will be Microsoft toast by next Christmas as Windows 7 is almost at the point of completion and may be going to Microsoft manufacture by June or July this year. But I doubt it will be in the shops before Xmas or early spring 2010. If you can wait for windows 7 I would as some of the windows 7 features do look interesting.
**Timing is everything dear boy!! timing (as well as cash of course).
Kind Regards Ivan
MCSE trained, many years in IT.