Edit 2009-11-10: if you are a developer make sure to check my colored logcat tool

I have seen that it can be a pain the ass to install the Android usb drivers used for debugging, so I put here the steps I made and successfuly got the Android to debug correctly.

1. install Samsung PC Studio 3  v3.2.3 IE2 to get the normal usb drivers. My link was http://lfiles3.brothersoft.com/internet/mobile/Samsung_PC_Studio_321_GJ9.exe

2. connect the Samsung Galaxy Android device(at this time USB debugging is turned off - see #4). Let Windows install the new hardware - the Samsung drivers.

You can now access the SD card on your device. You will see a USB symbol in the notification bar of the phone at the top. Pull it down and you will see "USB connected. Select to copy files/from your computer". Enable it and you will have access to the SD card.

Next steps are for development only!

3. modify c:\android-sdk-windows-1.5_r3\usb_driver\x86\android_usb.inf

under the [Google.NTx86] entry add
; SAMSUNG GALAXY
%USB\VID_04E8&PID_6640.DeviceDescRelease%=androidusb.Dev, USB\VID_04E8&PID_6640
%USB\VID_04E8&PID_6640&MI_04.DeviceDescRelease%=androidusb.Dev, USB\VID_04E8&PID_6640&MI_04
%USB\VID_04E8&PID_6640.DeviceDescRelease%=androidusb.Dev, USB\VID_04E8&PID_6640

under the [Strings] entry add
; SAMSUNG GALAXY
USB\VID_04E8&PID_6640.DeviceDescRelease="SAMSUNG GALAXY"
USB\VID_04E8&PID_6640&MI_04.DeviceDescRelease="SAMSUNG GALAXY Composite ADB Interface"
USB\VID_04E8&PID_6640.DeviceDescRelease="SAMSUNG GALAXY Bootloader"

Some people have reported the MI_04 combination above is not working; you may want to try MI_1 to MI_4 to be sure.

4. go to the phone -> Settings -> Applications -> Development -> enable USB debugging

5. Windows will ask for a new driver - this is used for debugging. Point the driver search to c:\android-sdk-windows-1.5_r3\usb_driver\x86\.

You should now be able to use debugging on the Samsung Galaxy Android.

Tips on debugging Samsung Galaxy Android:

1. to check if you can debug on the Android, use “adb devices”
I have
C:\>adb devices
List of devices attached
I7500wJLU2AuEy0 device
This entry is for my Samsung Galaxy I7500 Android phone.

2. use “adb logcat” to see the live and past Android logs. This is probably the most used command.

3. check out the documentation to see how to install and remove applications from the Android phone: http://developer.android.com/intl/de/guide/developing/tools/adb.html

Good luck and have fun!

Edit 2009-09-28: also un/check(depending on your needs) the "Mass Storage only" option under Settings/About phone.