This mirrors my experience; while I beleive the OP does have issues in his environment i's certainly not something inherant to Vista 64/Tortoise SVN
QFT. I've only had a 64-bit workstation for the last three years, running Tortoise from 1.4 to the latest 1.5.x. I would go so far as to characterize the experience as 'rock solid'
Look at the date you commenting clowns! Comments didn't exist on SO in August 2008, and those of us who were posting then don't need lectures about how to use them now...