If you are in the Main Menu and you want to create a new Driver
Profile, select Create from the Profile Manager Menu.

When you start a new driver profile, you will not have any of the
progress (unlocked cars, parts, or progress through Career Mode)
that you had in your old profile. (You can always log back in under
your original profile if you want to go back).

Manual Saves: Your game can be manually saved by accessing the Profile
Manager Menu and selecting Save.

NOTE:
Saving your profile saves your game progress. When you make a save game,
you are saving your progress in Career Mode, the number of cars,
car upgrades, and tracks you have unlocked, and any modifications you
have made to your cars.

The final game save directory is located at:
\Documents and Settings\PC Login ID\Local Settings\Application Data\NFS Underground 2

Substitute your actual Login ID for the PC Login ID mentioned above.