Transfering files from XP hard drive to Windows 7

No need to disable UAC. Just connect the second drive and access the files. You may run into "permission denied" issues (depending on where the files are on the disk). No problem, just right-click on the parent folder and take ownership. I have done the same for multiple disks without issue.

BTW, DocBrown's cable is a great solution. There are many such cables available for IDE and SATA drives...and you can get them extremely inexpensively. Much easier than cracking open the case for such a transfer. I went a little higher end since I connect such drives rather frequently...so I have something like what is pictured below...but the concept is the same. It's just a little faster to drop one into a dock....and it takes up less desk real estate for me. :)

cheers,
Steve

I am trying to do this now with the tri head adapter. The drive shows up as drive F but I cannot access it with out formatting it. The warning say's all data will be lost. Any suggestions?

If you're getting a message that the drive needs to be formatted before you can use it, that means the file system on it is already corrupted and unreadable. You might be able to use some recovery software to get some of the files back, but I think you're pretty much done with that old drive.

One possible other alternative, not too likely, I had an older USB/IDE enclosure, probably 5 years old and it would not handle my new drive because it was larger than 120GB. Using the new 500GB drive in this older adapter the new computer reported that the drive needed to be formatted. When I attached the same drive with a mew adapter, it worked fine and the data was accessible.