So I have a link in users profile page to go into thier personal album. but now trying to have  it go into thier presonal album under 'simple view' mode...

I took:

 'U_PERSONAL_GALLERY' => append_sid('album.' . $phpEx . '?user_id=' . $userdata['user_id']),

and added cat_id=4&mode=all& after ? so that its' '?cat_id=4&mode=all&user_id='  but that's not working .. it works, but category 4 is mine, heh.

I'm guessing I would do something like...
'U_PERSONAL_GALLERY' => append_sid('album.' . $phpEx . '?cat_id'?user_id=' . $userdata['user_id'] . $userdata['cat_id']),

:edit: ouch, that was ugly..

Any Ideas?

There is already a link for what you want in the user's profile page.
It's the small icon of a magnifiying glass.