The permissions thing you talk about is the new UAP. (User Account Protection) It is geared toward helping users in stopping fly by installs of viruses, malware and spyware. As i know the purpose of this feature and think that it can be a great thing. I also know how annoying it can be since i have used Vista since it was still Longhorn.
Best advice i can give in this situation is if you can live with it do so. It will only offer valuable security. If it becomes to much of a annoyance you can turn it off in the Control Panel. Under User Accounts. You will have to restart the machine in order for it to take effect.
With having it off you will be able to operate as you do on XP but be warned with Anti-Virus apps hard to find that work on Vista if you visit some shady sites or download some less than perfect files
you can be affected.