Try This, it worked for me on XP pro
Follow advice on other threads and download any software like Net framework 3.5 etc from microsoft updates, just go to start, all programs microsoft updates and choose custom, install everything that it shows to be sure that xp is fully up to date. Download the latest KIES program from Samsung if you already have not done so. You may need mirosoft office installed or at least MS Outlook (not EXpress) before you install Kies
Go to control panel / Add remove programs on pc.
Uninstall the "samsung drivers" that were installed with the Kies program but leave Kies program alone.
switch Samsung phone to mass storage mode and Connect USB cable both ends
Xp should then detect new hardware, go to start, control panel, System, hardware, device manager, universal serial bus controlers, your samsung phone will be connected to one of these, click on the one that appears to be connected and go to the drivers tab " Install Drivers" choose automaticly to install, it should detect the hardware and install the drivers, repeat this for all other items that it asks for, or any yellow question marks against any bits of hardware that resembles storage device or a phone.
It should also show as a "storage device",in the list, in device manager, if it has a yellow Question mark against it, again, click on it and go to drivers tab and click on the driver tab and click the install drivers and choose automaticly install.
Unplug USB and set phone back to samsung KIES mode, on the USB connect mode, of phone, open KIES and the phone should connect, well, mine did! Hope it works with yours! Let me know I'll cross my fingers for you!