If you are used to OSX' natural scrolling and you're switching between Windows 7 you might miss the natural scrolling feature in OSX. However, there's nothing to worry about - there's a fix :)
1. Go to your device manager and find your device (your mouse or trackpad)
2. Find your device's Hardware ID.
2. Open regedit.exe
3. Lookup the following thing: HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Enum/HID/<Hardware ID>/Device Parameters
4. Change the key named FlipFlopWheel from 0 to 1.
If you want to switch back just change the value from 1 to 0.