Ok, there should be a diagram on your hard drive when you take it out. It might be a sticker on the top, or it might be a couple of letters by the pins themselves. If there are letters above the pins, they usually look like this:
M C S
A S L
Line it up with the pins that says SL (for Slave).
Now, having said this, I see a couple of problems:
First of all, most windows programs store some information in the registry, so even if you mount that hard drive as a slave, the program information will not be in the windows xp registry and might not work (but give it a try as there might not be anything critical in the registry).
Secondly, if the program is not designed to run in Windows XP, you might have to set the compatibilty mode to run as if it were in Windows 98. To do this, right click on the program and select Properties. There will be a tab that says compatibility. Set this to Windows 98.
* You can even try the above with the program on your CD too to see if it works for installation.
Better things I would try first though:
1) Most cameras (unless they are really old) do not need special software to be used under Windows XP. Just plug the USB cable in, and they usually show up as a drive under My Computer.
2) Check the company website for Windows XP drivers for that model of camera.
3) If your camera uses a memory card, buy a cheap card reader, then stick the card in the card reader rather than plugging the camera directly into the computer. (This is generally the better option - at least in my opinion).
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If none of this works, then the last thing that would work would be to unplug the power and data cable from your new harddrive, and plug your old one in as master instead. Save your pictures and then set this one as slave and plug your new one in as master again. This way you can read your pictures off your old hard drive. One problem with this (despite being a big hassel) is that it will find new hardware (motherboard etc.) and might cause problems.
The other solution that would also work would be to use your old computer, then save your pictures. Then move the hard drive as a slave to your new computer. This involves moving your new comptuer out and putting the old computer in its place (since you only have one monitor). Or, if you have Internet access on this computer, e'mail them to yourself or upload to ebay etc.
I know these last two options aren't desired, but I included them here for completeness and as a last resort.