Joe, while there are certainly more similarities between Bush and McCain than there are between Bush and Obama, I don't think your list is quite fair. In particular, you mention torture - that's an issue on which McCain has gone adamantly against his party. Other issues on which he would be extremely different from Bush include environment and immigration. I am also hoping that while he did "change his mind" on the Bush tax cuts, his original inclinations would mean he wouldn't want to cut them left and right as Bush did.
With Obama, I just don't know which Obama to believe. I rather dislike the Obama I see on the stump, spewing off populist slogans (I, for one, do believe in NAFTA) and promising way more than any president could ever deliver. OTOH, I am more or less OK with Obama's actual platform - it contains some very ingenious ideas on simplifying tax collections (people whose only income is a salary and bank interest would get their tax forms in the mail already automatically filled in by the IRS computer, as this information is reported automatically - a simple thing that would save so much money and headaches for both the taxpayers and the government), a more reasonable health care proposal than what Clinton suggests, and rather moderate trade policies.
All in all, the only way I am voting for Obama in the general elections is if I just can't live with the VP McCain chooses (such as Huckabee).