The big rush to Vista that Microsoft was hoping for never materialized and with some good reasons. If you buy a new PC, you're going to be stuck with Vista whether you like it or not. Part of the abysmal response to Vista was due to (in part) pc manufacturors building pcs with inadequate hardware to run Vista properly. A PC needs at least 1 gig of memory and I would recommend dual core processor as well.
But is it right for you? If you use a lot of older software applications (or older hardware), definitely not. Quite a few older software programs out there are not Vista compatible and the companies that wrote them haven't (or aren't planning) released a patch to make them Vista ready. Same thing for hardware drivers. You may be forced to buy a piece of hardware to get a compatible driver. If you were thinking of upgrading your OS on your current machine to Vista, read the machine reqs I posted above before doing so. You can install it on a machine with less than the posted reqs, but you won't enjoy working on it. Vista requireds a beefy rig just to run the OS. To get good performance, I wouldn't run it on anything less than an Athlon X2 4800+ processor (or Intel Core 2 2.5 gigahertz processor) and 2 Gigs of memory. The reason that Vista needs more processing and memory is the visual display and backend. Vistas is very, very pretty, but that beauty comes at a premium. There are also a lot of extra security and permissions controls built in as well that are running in the background. Combined it demands a higher level of hardware to run effectively.
If you have any questions, please feel free to email me. - Charles