Donations to Bush/Cheney go to their legal fund after the nomination. They can't use that for anything other than for legal purposes. GOP donations can be used for anything.
The problem with donating to the GOP or the RNC (and the reason I never do) is that they use it to fund GOP candidates anywhere in the nation ... NOT necesssarily Bush. That is not for me.
That is also the reason I do not donate to the GOP in California ... but to the candidate. Much better IMO.