On a Windows XP system, there are 3 basic types of user accounts: Administrator, Limited User, and Guest.
Generally speaking, in order to install programs, you need to do this in the Administrator account. The reason is that a Limited user account blocks access to a number of areas of the computer. The Administrator can actually set things up to prevent a Limited user from installing anything at all.
So, for what you want to accomplish: 1st make sure that what you want to install is legitimate and is compatible with your system. The website for your camera that provides the downloads should tell you if they are compatible or not. Please note. If you saved the downloads to the desktop, you will need to save them to a different folder in order to get to the files when in the other account. The My Documents folder should work. The administrator can see the My Documents folders for all the accounts.
Once you have determined all that, then if you are in a Limited User account, log out of it then go into the Administrator account in order to install the drivers. Once they are installed, you can log back out of the Administrator account then log back into the Limited User account.
Note: While installing, if you get a question about whether you should make the program available for all users or just for me, choose "all users". If you don't, you won't have access to it from the limited user account.