Hey Michelle, welcome to the forums first of all, and you seem a tad bit confused
Hard drives will work on any system, 64bit or not.
All you may have to do is format the hard drive (delete everything off it) and then install Windows XP again after upgrading since the Windows setup will think its a new PC, and it doesn't like this, so its not the hard drives fault.
The type of hard drive I feel most comfortable with, and is the easiest one to install is a standard IDE drive, and this just plugs in and installs straight away when asked, rather than one called a SATA drive which needs drivers before installing Windows, etc, so i'd avoid it for someone who might have trouble installing one.
There are no performance increases from IDE to SATA anyway, so yeah, stick with IDE
1) The best one to get:
Thats a rather hard question as there a few good companies, but aim for one with as much space as you need (usually 60gb up now), and one with a 7200 revolutions per minute spinning speed which will make the hard drive faster, but all come with that speed as standard now. You definetly won't need one with a spinning speed of 10,000RPM, and these are really expensive at the moment.
2) None come with disk copying software, as you can just buy them, like Nero. These tend to come with DVD recordable drives.
Windows XP too, actually comes with its own basic one that'll copy a disc to a CD-Recordable disc.
3) If your talking about the hard drives that come with Dell and other companies that allow you to go back to what you had on your computer originally if things fail, these do not come as standard with hard drives you buy from the shops, and again, will have to be installed afterwards after buying specialist software.
This isn't a problem though, so don't worry, as this software is easily gotten hold of to backup your hard drive. This should be done regularily anyway.
you could always get a DVD copier, and back up your hard drive using that, if your scared of losing valuable data, and thats always best to do, or get hold of a USB device to store the needed data which is another good way of backing up.
I hope this helps.