The Tab should be recognized by your computer without the need for any drivers. Kies is a useful tool for some but it can be faster and easier to just connect the device and go to My Computer and you should see it as an external hard drive.
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If you are running windows XP you may run into a problem. The Tab does not play nice with all pc's running XP. I had an XP machine and the tab would NOT connect to it no matter what I did. Drivers included. I was desperately in need of a new laptop so I upgraded to a new one with windows 7. I then connected the tab and it was instantly recognized. I'm not saying that this is the case for everyone, but others have had the same problems I had with XP. So, if you're running XP then that may be your issue. Just something to be aware of and take into consideration.
LOL. This is one of the most misinformed posts I've read in a while. If your PC can read it as mass storage, that means you have the hardware drivers for it. If you dont have the proper and specific hardware drivers, not even a basic flash drive storage would work. Everything you connect to a PC (mice, external hard drives, cellphones, dongles), needs drivers to work. Some computers are able to download the drivers on their own without the need for installing Kies. However, Kies is good to have on your computer for the mere convenience of say, official updates. Not everyone wants to flash buggy custom ROMs, even if faster. Also installation of Kies would bring the latest official version of the needed drivers, including drivers PC's dont usually download by themselves, like MTP drivers.
Using the Tab as mass storage may or may not need new drivers for your PC, simply because you may have had another device which uses generic drivers that recognize the Tab. If his PC had those, the moment he connected his device to PC, it should have been recognized even without Kies installed on his PC, which in this case, drivers seem to have never been installed properly.
Second, the XP problem is an issue of wrong drivers. XP, Vista, 7, all have separate sets of drivers. So even if you download the drivers, if they aren;t compatible with your OS, nothing will happen.