Those are actually set on Googles servers I believe BUT in order to know who you are the standard practice is to place a cookie in your coockies cache to identify you.
If you have accept cookies turned off or you frequently wipe your coockies/cache files then that'll remove any personalization from a lot of web sits.
Cookies are "evil" when used for evil but they do have an actual working purpose and that kind of thing is exactly what they were meant for
[edit] heh Johnathan typed faster than me

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