Yes, your PC will run Vista graphics. However, there are four levels of Vista graphics capability that demand increasing -- maybe even cutting edge -- graphics cards. What you want may not be a level that your PC can deliver.
The attached article on WindowsBlinds 5 suggests the opportunity to try out this windowing-intensive graphics shell for Windows XP. If your PC does not choke, I suspect it will do adequately or better with the Avalon wizz-bang GUI in Vista.
And as a side benefit, WindowsBlinds 5 will make your PC look as close to a Mac running OS X as it is ever likely to get. Enjoy.