Are you sure a Vista compatible version was out at the time? It did take awhile, you know.
A lot of the "VISTA IS TERRIBLE" hype came from nerds mad about driver issues, or people trying to use software not compatible with Vista yet. (Which is ironic that so many people are upgrading from Vista to 7, because it's just going to make them more likely to encounter problems in incompatible software.) SP1 did fix all that, and as long as you have enough ram and take all the precautions you need to for XP, like making sure you don't do everything you can to slow it down, or reformatting once in awhile, Vista is fine.
If you're getting a new computer and can choose, go with 7 just because you're likely to get a computer with better specs to support what 7 needs anyway. But if you're spending your own money or thinking about upgrading I really don't see the point in trying to get 7 over Vista unless you're really never going to upgrade anything ever, or care about DX11.