Neither Windows XP nor Vista requires a driver for this camera as they both use the built-in PTP drivers to communicate with the camera. Therefore the disc is not a requirement to download your pics if either of these is your computer's OS.
If your computer isn't picking up the camera it's likely due to either incorrrectly configured computer services or interfering software or hardware on your PC. Such things as multifunction printers, scanners, web cams, and other installed camera software are number one culprits. If your PC has any of these devices, unhook them temporarily from your PC and stop their software programs from running by right-clicking on their programs' icons in the bottom right hand corner of your computer and clicking exit or stop. Then retry your camera connection.
Also always remember to put the camera into PLAYBACK mode before attempting a detection and download.
Call Canon Tech Support at 1-800-828-4040 for step by step assistance if needed.
Hope this helps.
P.S. You can order another CD from Canon at a nominal fee
and you can download the latest software updates from
their site at www.powershot.com
. Just click on the
Download Library link on the home page, enter your
camera in the drop down menus, and download any
update versions of the software from the default down-
load page. Just remember these are not full versions -
only UPDATES. Good luck!