2006 is going to be rough on a 7900GT, but you should still run it to get a good idea of how your system is performing... don't let the low fps's get you down though, real games will run a lot faster in most cases & some of those tests will humble my 8800GTX.
2005 will look quite a bit better & be a lot less painful to watch, but its not as useful as an actual tool.
2003 is great for an ego-boost & some eye-candy, but not much else.