Vista Kernel: It was recently replaced in the SP1 update to be the same as Windows 2008 server. I don't think the kernel is the problem with Vista, it's the fat bloated GUI.
That and the glaring privacy issues Microsoft created.
Windows 7: Testing friends of mine are saying comparatively speaking Windows 7 makes Vista feel like Windows ME and that even at this stage it is much better than Vista.
I've been comparing Vista to ME almost since it came out.