Screwed Up Permissions

I recently purchased a new computer with Windows Vista Home Premium 64-bit as my os. I took out the hard drive on my old computer, which ran Windows XP Professional, and put it in my new computer. Now I was able to transfer many files over from my old hard drive, to my new hard drive. However, when I tried to transfer my My Documents folder, I keep getting an error message telling me I do not have the right permissions. Now I realize this was probably due to the fact that my My Documents folder was probably under another user on Windows XP. I've tried to change the owner of the folder to my user account in Windows Vista, however, I fiddled around a bit with the permissions before that and now I cannot open certain folders and files, I can open a folder but cannot open any subfolders, etc. Its basically an absolute mess. I'm not very proficient when it comes to setting proper permissions and so forth. Any help on how I can handle this situation and get my data in the My Documents folder over to my new hard drive would be greatly appreciated.