A lot of laptops don't have built in memory card readers.... and those that do mostly only handle SD and smaller cards... But not Compact Flash, such as the XTi uses.
It sounds as if there isn't a driver installed on the computer, for the memory card reader you got. Check the card reader manufacturer's website and/or the Windows 8 website for compatible driver software. It's possible it doesn't exist, if the card reader is an older one that's not compatible with Win 8 (one reason I'm sticking with Win 7 on my computers).
Your laptop probably has several different methods of connecting to external devices. A common one is a USB port. There are USB2, and now much faster USB3 memory card readers. Some laptops also have Firewire 400 or 800 ports, and there are card readers designed to work with those, too.
If your computer has a USB port and you have the USB cable that came with your camera, you should be able to connect the camera directly to the laptop and download from it, without a card reader at all. This is generaly pretty slow, so not something I recommend doing all the time. It's better to use a card reader (which also allows you to use multiple cards and keep shooting while another one is downloading).
You might need to install a Windows 8 version of the Canon software on your computer before it will be able to communicate with the camera. (I just looked and don't see a driver for the camera, but that probably means it's already built into the Win 8 operating system.)
Some laptops also have a PCMCIA slot. There are Compact Flash readers made for those, too... and they download very fast. PCMCIA memory card readers can be a little tricky to load the card into, but if not doing that often it's not all the big a deal.
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
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