If you're using 2.1 (eclair),
1. Disconnect your USB cable from your phone.
2. Go to Settings > About phone > USB Settings > Mass Storage
3. Connect your USB cable to your phone.
4. Wait for your Windows to download the drivers (if it's your first time connecting)
5. When the drivers are installed, pull down Notification menu, click on the thing that allows you to Mount your phone and Mount (not sure what it's called).
6. After a few seconds, a Removable Disk (mine is L:, not sure what yours is) should appear and you can open the files and drag and drop stuff from your PC to your phone or vice versa.
If you're using 2.2 (froyo),
1. Disconnect your USB cable from your phone.
2. Go to Settings > Wireless and network > USB Settings > Mass Storage
3. A screen should appear with an Android logo with an option to Connect USB, click it.
4. Wait for your Windows to download the drivers (if it's your first time connecting)
5. After a few seconds, a Removable Disk (mine is L:, not sure what yours is) should appear and you can open the files and drag and drop stuff from your PC to your phone or vice versa.
To check if you're using 2.2 or 2.1, go to Settings > About phone and check the Firmware Version.
Hope it helps
