At the 'Options' menu select 'Passwords' and enter the following passwords without the quotes to unlock the effect you want. You'll know if you've entered the password correctly as you'll hear a confirmation sound.

Unlock ALL Clubs:
Enter the password 'PROSHOP'.

Unlock ALL Golfers:
Enter the password 'GAMEFACE'.

Unlock Mizuno Items:
Enter the password 'RIHACHINRIZO'.

Unlock Nike Items:
Enter the password 'JUSTDOIT'.

Unlock Bridgestone Items:
Enter the password 'NOTJUSTTIRES'.

Unlock Buick Items:
Enter the password 'THREESTRIPES'.

Unlock Cobra Items:
Enter the password 'SNAKEKING'.

Unlock EA Items:
Enter the password 'INTHEGAME'.

Unlock Grafalloy Items:
Enter the password 'JUSTSHAFTS'.

Unlock J.Lindeberg Items:
Enter the password 'JLINDEBERG'.

Unlock Cleveland Golf Items:
Enter the password 'CLEVELAND'.

Unlock Precept Items:
Enter the password 'GUYSAREGOOD'.