To run Vista, you will need an 800 Megahertz processor, 512Mb of memory and a VGA adapter.

However, in order to run Vista Premium standard, you will need a 1.5 Gigahertz processor with 1 Gigabyte memory and a 128 Megabytes DirectX 9 graphics adapter.

That said, with 512 Megabytes of memory, you should be able to run Vista Home Basic. I have experimented removing memory and under-clocking my processor just to see how near bare minimum hardware runs Vista.

It DOES run Vista, but I'd recommend running one application at one time or not having any background running third-party applications.

Windows Vista delivers - performance, productivity and entertainment.

Performance - your hardware is up for it (WIE 3.0 +)
Productivity - thanks to Windows Live and Office 2007 seamlessly working with Vista
Entertainment - IE7, Games Explorer, DirectX 10, support for latest hardware

Most of us have issues with 'performance' and 'productivity'. Seriously, if your machine can't handle Vista, you need to think about upgrading and/or getting a new machine. I see all the reasons and more than ever with SP1 to get Windows Vista today.