Windows XP is a bit of a funny beast when it comes to USB. Not only do you have to install the software and drivers as a system administrator (this is as it should be), but it will flatly refuse to use those drivers until you've also plugged the device into a USB port while logged on as an Administrator. If you're a normal user, it just won't work.
Even better, just because you've plugged it into one port on a PC, that doesn't mean that the OS will use the driver for that same device if it is then plugged into another USB port. It's just plain weird.
It could be something like this, or it could well be that the drivers are just rubbish. I just don't know.
Anyway, Pup's suggestion of using a card reader is a good one. All decent card readers are supported by the OS without needing separate drivers or other software, and can usually transfer images at much higher speeds over USB than a camera can.
Me, I have one of
Sandisk's multi-format readers. Although I am unlikely to have to deal with xD or Smartmedia or anything like that, I do have cameras that use CompactFlash and SD, and I've also used it to get stuff off a family member's MemoryStick, too.
It's fast, it's simple to use, and works on pretty much any current computer platform you can think of (windows, Mac & Linux). It's not the cheapest reader out there, but it's always served the missus and I well...